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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
59895 | How do I get the directory where a Bash script is located from within the script itself? | 6,405 | 2008-09-12 20:39:56 | <p>How do I get the path of the directory in which a <a href="http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="noreferrer">Bash</a> script is located, <em>inside</em> that script?</p>
<p>I want to use a Bash script as a launcher for another application. I want to change the working directory to the one where th... | 2,834,402 | 2,908 | 2025-06-10 04:21:43 | 246,128 | 8,291 | 2008-10-29 08:36:45 | 7,412 | 2025-05-22 03:57:59 | https://stackoverflow.com/q/59895 | https://stackoverflow.com/a/246128 | <pre><code>#!/usr/bin/env bash
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
</code></pre>
<p>is a useful one-liner which will give you the full directory name of the script no matter where it is being called from.</p>
<p>It will work as long as the ... | <pre><code>#!/usr/bin/env bash SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd ) </code></pre> <p>is a useful one-liner which will give you the full directory name of the script no matter where it is being called from.</p> <p>It will work as long as the ... | 218, 387 | bash, directory | <h1>How do I get the directory where a Bash script is located from within the script itself?</h1>
<p>How do I get the path of the directory in which a <a href="http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="noreferrer">Bash</a> script is located, <em>inside</em> that script?</p>
<p>I want to use a Bash script... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 16 | bash | # How do I get the directory where a Bash script is located from within the script itself?
How do I get the path of the directory in which a [Bash](http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29) script is located, *inside* that script?
I want to use a Bash script as a launcher for another application. I want to ... | ```
#!/usr/bin/env bash
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
```
is a useful one-liner which will give you the full directory name of the script no matter where it is being called from.
It will work as long as the last component of the path used to find the script is not a ... |
11304895 | How do I copy a folder from remote to local using scp? | 3,597 | 2012-07-03 05:17:58 | <p>How do I copy a folder from remote to local host using <code>scp</code>?</p>
<p>I use <code>ssh</code> to log in to my server.<br />
Then, I would like to copy the remote folder <code>foo</code> to local <code>/home/user/Desktop</code>.</p>
<p>How do I achieve this?</p>
| 3,900,240 | 1,469,282 | 2024-09-17 16:05:15 | 11,304,926 | 6,406 | 2012-07-03 05:21:39 | 774,116 | 2020-10-15 01:21:14 | https://stackoverflow.com/q/11304895 | https://stackoverflow.com/a/11304926 | <pre><code>scp -r user@your.server.example.com:/path/to/foo /home/user/Desktop/
</code></pre>
<p>By not including the trailing '/' at the end of foo, you will copy the directory itself (including contents), rather than only the contents of the directory.</p>
<p>From <code>man scp</code> (See <a href="http://man7.org/li... | <pre><code>scp -r user@your.server.example.com:/path/to/foo /home/user/Desktop/ </code></pre> <p>By not including the trailing '/' at the end of foo, you will copy the directory itself (including contents), rather than only the contents of the directory.</p> <p>From <code>man scp</code> (See <a href="http://man7.org/li... | 386, 390, 1231, 3149, 4330 | command-line, copy, scp, shell, ssh | <h1>How do I copy a folder from remote to local using scp?</h1>
<p>How do I copy a folder from remote to local host using <code>scp</code>?</p>
<p>I use <code>ssh</code> to log in to my server.<br />
Then, I would like to copy the remote folder <code>foo</code> to local <code>/home/user/Desktop</code>.</p>
<p>How do I ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 17 | bash | # How do I copy a folder from remote to local using scp?
How do I copy a folder from remote to local host using `scp`?
I use `ssh` to log in to my server.
Then, I would like to copy the remote folder `foo` to local `/home/user/Desktop`.
How do I achieve this? | ```
scp -r user@your.server.example.com:/path/to/foo /home/user/Desktop/
```
By not including the trailing '/' at the end of foo, you will copy the directory itself (including contents), rather than only the contents of the directory.
From `man scp` (See [online manual](http://man7.org/linux/man-pages/man1/scp.1.html... |
59838 | How do I check if a directory exists or not in a Bash shell script? | 4,553 | 2008-09-12 20:06:25 | <p>What command checks if a directory exists or not within a Bash shell script?</p>
| 3,495,129 | 4,120 | 2023-12-23 06:16:55 | 59,839 | 6,152 | 2008-09-12 20:07:06 | 4,120 | 2022-08-01 01:21:58 | https://stackoverflow.com/q/59838 | https://stackoverflow.com/a/59839 | <p>To check if a directory exists:</p>
<pre><code>if [ -d "$DIRECTORY" ]; then
echo "$DIRECTORY does exist."
fi
</code></pre>
<p>To check if a directory does not exist:</p>
<pre><code>if [ ! -d "$DIRECTORY" ]; then
echo "$DIRECTORY does not exist."
fi
</code></pre>
<hr />
<p>... | <p>To check if a directory exists:</p> <pre><code>if [ -d "$DIRECTORY" ]; then echo "$DIRECTORY does exist." fi </code></pre> <p>To check if a directory does not exist:</p> <pre><code>if [ ! -d "$DIRECTORY" ]; then echo "$DIRECTORY does not exist." fi </code></pre> <hr /> <p>... | 34, 387, 390, 1796, 1993 | bash, command, posix, shell, unix | <h1>How do I check if a directory exists or not in a Bash shell script?</h1>
<p>What command checks if a directory exists or not within a Bash shell script?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 18 | bash | # How do I check if a directory exists or not in a Bash shell script?
What command checks if a directory exists or not within a Bash shell script? | To check if a directory exists:
```
if [ -d "$DIRECTORY" ]; then
echo "$DIRECTORY does exist."
fi
```
To check if a directory does not exist:
```
if [ ! -d "$DIRECTORY" ]; then
echo "$DIRECTORY does not exist."
fi
```
---
However, as [Jon Ericson](https://stackoverflow.com/users/1438/jon-ericson) points out, s... |
89228 | How do I execute a program or call a system command? | 6,282 | 2008-09-18 01:35:30 | <p>How do I call an external command within Python as if I had typed it in a shell or command prompt?</p>
| 5,200,895 | 17,085 | 2025-11-04 02:52:45 | 89,243 | 5,961 | 2008-09-18 01:39:35 | 11,465 | 2023-05-19 23:52:54 | https://stackoverflow.com/q/89228 | https://stackoverflow.com/a/89243 | <p>Use <a href="https://docs.python.org/library/subprocess.html#subprocess.run" rel="noreferrer"><code>subprocess.run</code></a>:</p>
<pre class="lang-py prettyprint-override"><code>import subprocess
subprocess.run(["ls", "-l"])
</code></pre>
<p>Another common way is <a href="https://docs.python.o... | <p>Use <a href="https://docs.python.org/library/subprocess.html#subprocess.run" rel="noreferrer"><code>subprocess.run</code></a>:</p> <pre class="lang-py prettyprint-override"><code>import subprocess subprocess.run(["ls", "-l"]) </code></pre> <p>Another common way is <a href="https://docs.python.o... | 16, 390, 391, 1796, 2348 | command, python, shell, subprocess, terminal | <h1>How do I execute a program or call a system command?</h1>
<p>How do I call an external command within Python as if I had typed it in a shell or command prompt?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 19 | bash | # How do I execute a program or call a system command?
How do I call an external command within Python as if I had typed it in a shell or command prompt? | Use [`subprocess.run`](https://docs.python.org/library/subprocess.html#subprocess.run):
```
import subprocess
subprocess.run(["ls", "-l"])
```
Another common way is [`os.system`](https://docs.python.org/library/os.html#os.system) but you shouldn't use it because it is unsafe if any parts of the command come from out... |
638975 | How do I tell if a file does not exist in Bash? | 4,162 | 2009-03-12 14:48:43 | <p>This checks if a file exists:</p>
<pre><code>#!/bin/bash
FILE=$1
if [ -f $FILE ]; then
echo "File $FILE exists."
else
echo "File $FILE does not exist."
fi
</code></pre>
<p>How do I only check if the file does <strong>not</strong> exist?</p>
| 3,439,075 | 1,288 | 2024-06-18 10:32:34 | 638,980 | 5,614 | 2009-03-12 14:50:01 | 75,170 | 2022-07-17 00:26:03 | https://stackoverflow.com/q/638975 | https://stackoverflow.com/a/638980 | <p>The <a href="http://man7.org/linux/man-pages/man1/test.1.html" rel="noreferrer"><code>test</code></a> command (written as <code>[</code> here) has a "not" logical operator, <code>!</code> (exclamation mark):</p>
<pre><code>if [ ! -f /tmp/foo.txt ]; then
echo "File not found!"
fi
</code></pre>... | <p>The <a href="http://man7.org/linux/man-pages/man1/test.1.html" rel="noreferrer"><code>test</code></a> command (written as <code>[</code> here) has a "not" logical operator, <code>!</code> (exclamation mark):</p> <pre><code>if [ ! -f /tmp/foo.txt ]; then echo "File not found!" fi </code></pre>... | 387, 531, 724 | bash, file-io, scripting | <h1>How do I tell if a file does not exist in Bash?</h1>
<p>This checks if a file exists:</p>
<pre><code>#!/bin/bash
FILE=$1
if [ -f $FILE ]; then
echo "File $FILE exists."
else
echo "File $FILE does not exist."
fi
</code></pre>
<p>How do I only check if the file does <strong>not</strong... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 20 | bash | # How do I tell if a file does not exist in Bash?
This checks if a file exists:
```
#!/bin/bash
FILE=$1
if [ -f $FILE ]; then
echo "File $FILE exists."
else
echo "File $FILE does not exist."
fi
```
How do I only check if the file does **not** exist? | The [`test`](http://man7.org/linux/man-pages/man1/test.1.html) command (written as `[` here) has a "not" logical operator, `!` (exclamation mark):
```
if [ ! -f /tmp/foo.txt ]; then
echo "File not found!"
fi
``` |
229551 | How to check if a string contains a substring in Bash | 3,658 | 2008-10-23 12:37:31 | <p>I have a string in Bash:</p>
<pre class="lang-sh prettyprint-override"><code>string="My string"
</code></pre>
<p>How can I test if it contains another string?</p>
<pre class="lang-sh prettyprint-override"><code>if [ $string ?? 'foo' ]; then
echo "It's there!"
fi
</code></pre>
<p>Where <code>??<... | 3,391,086 | 30,773 | 2026-01-08 11:58:40 | 229,606 | 5,028 | 2008-10-23 12:55:24 | 21,632 | 2020-04-17 01:20:42 | https://stackoverflow.com/q/229551 | https://stackoverflow.com/a/229606 | <p>You can use <a href="https://stackoverflow.com/a/229585/3755692">Marcus's answer (* wildcards)</a> outside a case statement, too, if you use double brackets:</p>
<pre><code>string='My long string'
if [[ $string == *"My long"* ]]; then
echo "It's there!"
fi
</code></pre>
<p>Note that spaces in the needle string n... | <p>You can use <a href="https://stackoverflow.com/a/229585/3755692">Marcus's answer (* wildcards)</a> outside a case statement, too, if you use double brackets:</p> <pre><code>string='My long string' if [[ $string == *"My long"* ]]; then echo "It's there!" fi </code></pre> <p>Note that spaces in the needle string n... | 139, 387, 390, 4371, 10327 | bash, sh, shell, string, substring | <h1>How to check if a string contains a substring in Bash</h1>
<p>I have a string in Bash:</p>
<pre class="lang-sh prettyprint-override"><code>string="My string"
</code></pre>
<p>How can I test if it contains another string?</p>
<pre class="lang-sh prettyprint-override"><code>if [ $string ?? 'foo' ]; then
e... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 21 | bash | # How to check if a string contains a substring in Bash
I have a string in Bash:
```
string="My string"
```
How can I test if it contains another string?
```
if [ $string ?? 'foo' ]; then
echo "It's there!"
fi
```
Where `??` is my unknown operator. Do I use `echo` and `grep`?
```
if echo "$string" | grep 'foo';... | You can use [Marcus's answer (* wildcards)](https://stackoverflow.com/a/229585/3755692) outside a case statement, too, if you use double brackets:
```
string='My long string'
if [[ $string == *"My long"* ]]; then
echo "It's there!"
fi
```
Note that spaces in the needle string need to be placed between double quotes... |
4181703 | How to concatenate string variables in Bash | 3,611 | 2010-11-15 05:38:35 | <p>In PHP, strings are concatenated together as follows:</p>
<pre><code>$foo = "Hello";
$foo .= " World";
</code></pre>
<p>Here, <code>$foo</code> becomes <code>"Hello World"</code>.</p>
<p>How is this accomplished in Bash?</p>
| 5,351,453 | 170,365 | 2025-10-16 09:01:13 | 4,181,721 | 4,890 | 2010-11-15 05:41:36 | 227,665 | 2019-09-01 12:51:28 | https://stackoverflow.com/q/4181703 | https://stackoverflow.com/a/4181721 | <pre><code>foo="Hello"
foo="${foo} World"
echo "${foo}"
> Hello World
</code></pre>
<p>In general to concatenate two variables you can just write them one after another:</p>
<pre><code>a='Hello'
b='World'
c="${a} ${b}"
echo "${c}"
> Hello World
</code></pre>
| <pre><code>foo="Hello" foo="${foo} World" echo "${foo}" > Hello World </code></pre> <p>In general to concatenate two variables you can just write them one after another:</p> <pre><code>a='Hello' b='World' c="${a} ${b}" echo "${c}" > Hello World </code></pre> | 367, 387, 390, 6050, 7792 | bash, concatenation, shell, string-concatenation, syntax | <h1>How to concatenate string variables in Bash</h1>
<p>In PHP, strings are concatenated together as follows:</p>
<pre><code>$foo = "Hello";
$foo .= " World";
</code></pre>
<p>Here, <code>$foo</code> becomes <code>"Hello World"</code>.</p>
<p>How is this accomplished in Bash?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 22 | bash | # How to concatenate string variables in Bash
In PHP, strings are concatenated together as follows:
```
$foo = "Hello";
$foo .= " World";
```
Here, `$foo` becomes `"Hello World"`.
How is this accomplished in Bash? | ```
foo="Hello"
foo="${foo} World"
echo "${foo}"
> Hello World
```
In general to concatenate two variables you can just write them one after another:
```
a='Hello'
b='World'
c="${a} ${b}"
echo "${c}"
> Hello World
``` |
793858 | How to mkdir only if a directory does not already exist? | 2,998 | 2009-04-27 14:47:44 | <p>I am writing a shell script to run under the KornShell (ksh) on AIX. I would like to use the <code>mkdir</code> command to create a directory. But the directory may already exist, in which case I do not want to do anything. So I want to either test to see that the directory does not exist, or suppress the "File exis... | 2,292,191 | 73,371 | 2023-03-17 09:06:20 | 793,867 | 4,852 | 2009-04-27 14:49:46 | 69,755 | 2019-01-23 21:04:22 | https://stackoverflow.com/q/793858 | https://stackoverflow.com/a/793867 | <p>Try <a href="http://pubs.opengroup.org/onlinepubs/009695399/utilities/mkdir.html" rel="noreferrer"><code>mkdir -p</code></a>:</p>
<pre><code>mkdir -p foo
</code></pre>
<p>Note that this will also create any intermediate directories that don't exist; for instance,</p>
<pre><code>mkdir -p foo/bar/baz
</code></pre>
... | <p>Try <a href="http://pubs.opengroup.org/onlinepubs/009695399/utilities/mkdir.html" rel="noreferrer"><code>mkdir -p</code></a>:</p> <pre><code>mkdir -p foo </code></pre> <p>Note that this will also create any intermediate directories that don't exist; for instance,</p> <pre><code>mkdir -p foo/bar/baz </code></pre> ... | 390, 531, 989, 1964, 24423 | aix, ksh, mkdir, scripting, shell | <h1>How to mkdir only if a directory does not already exist?</h1>
<p>I am writing a shell script to run under the KornShell (ksh) on AIX. I would like to use the <code>mkdir</code> command to create a directory. But the directory may already exist, in which case I do not want to do anything. So I want to either test to... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 23 | bash | # How to mkdir only if a directory does not already exist?
I am writing a shell script to run under the KornShell (ksh) on AIX. I would like to use the `mkdir` command to create a directory. But the directory may already exist, in which case I do not want to do anything. So I want to either test to see that the direct... | Try [`mkdir -p`](http://pubs.opengroup.org/onlinepubs/009695399/utilities/mkdir.html):
```
mkdir -p foo
```
Note that this will also create any intermediate directories that don't exist; for instance,
```
mkdir -p foo/bar/baz
```
will create directories `foo`, `foo/bar`, and `foo/bar/baz` if they don't exist.
Some... |
592620 | How can I check if a program exists from a Bash script? | 3,215 | 2009-02-26 21:52:49 | <p>How would I validate that a program exists, in a way that will either return an error and exit, or continue with the script?</p>
<p>It seems like it should be easy, but it's been stumping me.</p>
| 1,298,786 | 2,687 | 2025-06-01 11:10:42 | 677,212 | 4,596 | 2009-03-24 12:45:20 | 58,803 | 2025-06-01 11:10:42 | https://stackoverflow.com/q/592620 | https://stackoverflow.com/a/677212 | <h2>Answer</h2>
<p>POSIX compatible:</p>
<pre><code>command -v <the_command>
</code></pre>
<p>Example use:</p>
<pre><code>if ! command -v <the_command> >/dev/null 2>&1
then
echo "<the_command> could not be found"
exit 1
fi
</code></pre>
<p>For Bash specific environments:</p... | <h2>Answer</h2> <p>POSIX compatible:</p> <pre><code>command -v <the_command> </code></pre> <p>Example use:</p> <pre><code>if ! command -v <the_command> >/dev/null 2>&1 then echo "<the_command> could not be found" exit 1 fi </code></pre> <p>For Bash specific environments:</p... | 387 | bash | <h1>How can I check if a program exists from a Bash script?</h1>
<p>How would I validate that a program exists, in a way that will either return an error and exit, or continue with the script?</p>
<p>It seems like it should be easy, but it's been stumping me.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 24 | bash | # How can I check if a program exists from a Bash script?
How would I validate that a program exists, in a way that will either return an error and exit, or continue with the script?
It seems like it should be easy, but it's been stumping me. | ## Answer
POSIX compatible:
```
command -v <the_command>
```
Example use:
```
if ! command -v <the_command> >/dev/null 2>&1
then
echo "<the_command> could not be found"
exit 1
fi
```
For Bash specific environments:
```
hash <the_command> # For regular commands. Or...
type <the_command> # To check built-in... |
965053 | Extract filename and extension in Bash | 2,918 | 2009-06-08 14:00:29 | <p>I want to get the filename (without extension) and the extension separately.</p>
<p>The best solution I found so far is:</p>
<pre><code>NAME=`echo "$FILE" | cut -d'.' -f1`
EXTENSION=`echo "$FILE" | cut -d'.' -f2`
</code></pre>
<p>This is wrong because it doesn't work if the file name contains mul... | 2,427,384 | 5,475 | 2025-08-17 16:24:24 | 965,072 | 4,538 | 2009-06-08 14:05:19 | 17,833 | 2025-03-21 07:22:40 | https://stackoverflow.com/q/965053 | https://stackoverflow.com/a/965072 | <p>First, get file name without the path:</p>
<pre class="lang-bash prettyprint-override"><code>filename=$(basename -- "$fullfile")
extension="${filename##*.}"
filename="${filename%.*}"
</code></pre>
<p>Alternatively, you can focus on the last '/' of the path instead of the '.' which shoul... | <p>First, get file name without the path:</p> <pre class="lang-bash prettyprint-override"><code>filename=$(basename -- "$fullfile") extension="${filename##*.}" filename="${filename%.*}" </code></pre> <p>Alternatively, you can focus on the last '/' of the path instead of the '.' which shoul... | 139, 387, 1062 | bash, filenames, string | <h1>Extract filename and extension in Bash</h1>
<p>I want to get the filename (without extension) and the extension separately.</p>
<p>The best solution I found so far is:</p>
<pre><code>NAME=`echo "$FILE" | cut -d'.' -f1`
EXTENSION=`echo "$FILE" | cut -d'.' -f2`
</code></pre>
<p>This is wrong becau... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 25 | bash | # Extract filename and extension in Bash
I want to get the filename (without extension) and the extension separately.
The best solution I found so far is:
```
NAME=`echo "$FILE" | cut -d'.' -f1`
EXTENSION=`echo "$FILE" | cut -d'.' -f2`
```
This is wrong because it doesn't work if the file name contains multiple `.`... | First, get file name without the path:
```
filename=$(basename -- "$fullfile")
extension="${filename##*.}"
filename="${filename%.*}"
```
Alternatively, you can focus on the last '/' of the path instead of the '.' which should work even if you have unpredictable file extensions:
```
filename="${fullfile##*/}"
```
Yo... |
5905054 | How can I recursively find all files in current and subfolders based on wildcard matching? | 3,144 | 2011-05-05 23:01:34 | <p>How can I recursively find all files in current and subfolders based on wildcard matching?</p>
| 5,129,961 | 302,064 | 2023-12-29 09:16:26 | 5,905,066 | 4,478 | 2011-05-05 23:03:37 | 82,219 | 2023-12-29 09:16:26 | https://stackoverflow.com/q/5905054 | https://stackoverflow.com/a/5905066 | <p>Use <a href="http://linux.die.net/man/1/find" rel="noreferrer"><code>find</code></a>:</p>
<pre><code>find . -name "foo*"
</code></pre>
<p><code>find</code> needs a starting point, so the <code>.</code> (dot) points to the current directory.</p>
<p>If you need <strong>case insensitive</strong> search use :<... | <p>Use <a href="http://linux.die.net/man/1/find" rel="noreferrer"><code>find</code></a>:</p> <pre><code>find . -name "foo*" </code></pre> <p><code>find</code> needs a starting point, so the <code>.</code> (dot) points to the current directory.</p> <p>If you need <strong>case insensitive</strong> search use :<... | 58, 390 | linux, shell | <h1>How can I recursively find all files in current and subfolders based on wildcard matching?</h1>
<p>How can I recursively find all files in current and subfolders based on wildcard matching?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 26 | bash | # How can I recursively find all files in current and subfolders based on wildcard matching?
How can I recursively find all files in current and subfolders based on wildcard matching? | Use [`find`](http://linux.die.net/man/1/find):
```
find . -name "foo*"
```
`find` needs a starting point, so the `.` (dot) points to the current directory.
If you need **case insensitive** search use :
```
find . -iname "foo*"
``` |
8467424 | Echo newline in Bash prints literal \n | 3,667 | 2011-12-11 21:01:54 | <p>How do I print a newline? This merely prints <code>\n</code>:</p>
<pre><code>echo -e "Hello,\nWorld!"
</code></pre>
<p>Output:</p>
<pre class="lang-none prettyprint-override"><code>Hello,\nWorld!
</code></pre>
| 3,688,424 | 187,644 | 2025-12-09 22:55:19 | 8,467,449 | 4,311 | 2011-12-11 21:04:56 | 56,338 | 2025-07-16 17:42:38 | https://stackoverflow.com/q/8467424 | https://stackoverflow.com/a/8467449 | <p>Use <code>printf</code> instead:</p>
<pre><code>printf 'Hello, \nWorld!\n'
</code></pre>
<p><code>printf</code> behaves more consistently across different environments than <code>echo</code>.</p>
| <p>Use <code>printf</code> instead:</p> <pre><code>printf 'Hello, \nWorld!\n' </code></pre> <p><code>printf</code> behaves more consistently across different environments than <code>echo</code>.</p> | 387, 3705, 13824 | bash, echo, newline | <h1>Echo newline in Bash prints literal \n</h1>
<p>How do I print a newline? This merely prints <code>\n</code>:</p>
<pre><code>echo -e "Hello,\nWorld!"
</code></pre>
<p>Output:</p>
<pre class="lang-none prettyprint-override"><code>Hello,\nWorld!
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 27 | bash | # Echo newline in Bash prints literal \n
How do I print a newline? This merely prints `\n`:
```
echo -e "Hello,\nWorld!"
```
Output:
```
Hello,\nWorld!
``` | Use `printf` instead:
```
printf 'Hello, \nWorld!\n'
```
`printf` behaves more consistently across different environments than `echo`. |
1825585 | Determine installed PowerShell version | 2,915 | 2009-12-01 11:30:03 | <p>How can I determine what version of PowerShell is installed on a computer, and indeed if it is installed at all?</p>
| 3,250,810 | 35,483 | 2025-11-15 13:22:28 | 1,825,807 | 3,878 | 2009-12-01 12:12:38 | null | 2020-01-02 07:33:10 | https://stackoverflow.com/q/1825585 | https://stackoverflow.com/a/1825807 | <p>Use <code>$PSVersionTable.PSVersion</code> to determine the engine version. If the variable does not exist, it is safe to assume the engine is version <code>1.0</code>.</p>
<p>Note that <code>$Host.Version</code> and <code>(Get-Host).Version</code> are not reliable - they reflect
the version of the host only, not t... | <p>Use <code>$PSVersionTable.PSVersion</code> to determine the engine version. If the variable does not exist, it is safe to assume the engine is version <code>1.0</code>.</p> <p>Note that <code>$Host.Version</code> and <code>(Get-Host).Version</code> are not reliable - they reflect the version of the host only, not t... | 526, 5792 | powershell, version | <h1>Determine installed PowerShell version</h1>
<p>How can I determine what version of PowerShell is installed on a computer, and indeed if it is installed at all?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 28 | bash | # Determine installed PowerShell version
How can I determine what version of PowerShell is installed on a computer, and indeed if it is installed at all? | Use `$PSVersionTable.PSVersion` to determine the engine version. If the variable does not exist, it is safe to assume the engine is version `1.0`.
Note that `$Host.Version` and `(Get-Host).Version` are not reliable - they reflect
the version of the host only, not the engine. PowerGUI,
PowerShellPLUS, etc. are all host... |
192249 | How do I parse command line arguments in Bash? | 2,627 | 2008-10-10 16:57:19 | <p>Say, I have a script that gets called with this line:</p>
<pre><code>./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile
</code></pre>
<p>or this one:</p>
<pre><code>./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile
</code></pre>
<p>What's the accepted way of parsing this such that in each case (o... | 2,195,200 | 1,512 | 2025-05-30 12:27:53 | 14,203,146 | 3,687 | 2013-01-07 20:01:05 | 117,471 | 2024-03-18 06:12:10 | https://stackoverflow.com/q/192249 | https://stackoverflow.com/a/14203146 | <h4>Bash Space-Separated (e.g., <code>--option argument</code>)</h4>
<pre class="lang-bash prettyprint-override"><code>cat >/tmp/demo-space-separated.sh <<'EOF'
#!/bin/bash
POSITIONAL_ARGS=()
while [[ $# -gt 0 ]]; do
case $1 in
-e|--extension)
EXTENSION="$2"
shift # past argument... | <h4>Bash Space-Separated (e.g., <code>--option argument</code>)</h4> <pre class="lang-bash prettyprint-override"><code>cat >/tmp/demo-space-separated.sh <<'EOF' #!/bin/bash POSITIONAL_ARGS=() while [[ $# -gt 0 ]]; do case $1 in -e|--extension) EXTENSION="$2" shift # past argument... | 387, 531, 1231, 2313, 19020 | arguments, bash, command-line, getopts, scripting | <h1>How do I parse command line arguments in Bash?</h1>
<p>Say, I have a script that gets called with this line:</p>
<pre><code>./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile
</code></pre>
<p>or this one:</p>
<pre><code>./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile
</code></pre>
<p>What's th... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 29 | bash | # How do I parse command line arguments in Bash?
Say, I have a script that gets called with this line:
```
./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile
```
or this one:
```
./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile
```
What's the accepted way of parsing this such that in each case ... | #### Bash Space-Separated (e.g., `--option argument`)
```
cat >/tmp/demo-space-separated.sh <<'EOF'
#!/bin/bash
POSITIONAL_ARGS=()
while [[ $# -gt 0 ]]; do
case $1 in
-e|--extension)
EXTENSION="$2"
shift # past argument
shift # past value
;;
-s|--searchpath)
SEARCHPATH="$2"
... |
818255 | What does " 2>&1 " mean? | 3,260 | 2009-05-03 22:57:00 | <p>To combine <code>stderr</code> and <code>stdout</code> into the <code>stdout</code> stream, we append this to a command:</p>
<pre><code>2>&1
</code></pre>
<p>For example, the following command shows the first few errors from compiling <code>main.cpp</code>:</p>
<pre><code>g++ main.cpp 2>&1 | head
</cod... | 1,963,820 | 30,529 | 2024-11-07 14:50:17 | 818,284 | 3,676 | 2009-05-03 23:04:53 | 40,005 | 2022-07-17 06:18:24 | https://stackoverflow.com/q/818255 | https://stackoverflow.com/a/818284 | <p>File descriptor 1 is the standard output (<code>stdout</code>).<br>
File descriptor 2 is the standard error (<code>stderr</code>).</p>
<p>At first, <code>2>1</code> may look like a good way to redirect <code>stderr</code> to <code>stdout</code>. However, it will actually be interpreted as "redirect <code>std... | <p>File descriptor 1 is the standard output (<code>stdout</code>).<br> File descriptor 2 is the standard error (<code>stderr</code>).</p> <p>At first, <code>2>1</code> may look like a good way to redirect <code>stderr</code> to <code>stdout</code>. However, it will actually be interpreted as "redirect <code>std... | 34, 387, 390 | bash, shell, unix | <h1>What does " 2>&1 " mean?</h1>
<p>To combine <code>stderr</code> and <code>stdout</code> into the <code>stdout</code> stream, we append this to a command:</p>
<pre><code>2>&1
</code></pre>
<p>For example, the following command shows the first few errors from compiling <code>main.cpp</code>:</p>
<pre><code>g++... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 30 | bash | # What does " 2>&1 " mean?
To combine `stderr` and `stdout` into the `stdout` stream, we append this to a command:
```
2>&1
```
For example, the following command shows the first few errors from compiling `main.cpp`:
```
g++ main.cpp 2>&1 | head
```
But what does `2>&1` mean? | File descriptor 1 is the standard output (`stdout`).
File descriptor 2 is the standard error (`stderr`).
At first, `2>1` may look like a good way to redirect `stderr` to `stdout`. However, it will actually be interpreted as "redirect `stderr` to a file named `1`".
`&` indicates that what follows and precedes is a *... |
4037939 | PowerShell says "execution of scripts is disabled on this system." | 3,013 | 2010-10-27 21:39:29 | <p>I am trying to run a <code>cmd</code> file that calls a PowerShell script from <code>cmd.exe</code>, but I am getting this error:</p>
<blockquote>
<p><code>Management_Install.ps1</code> cannot be loaded because the execution of scripts is disabled on this system.</p>
</blockquote>
<p>I ran this command:</p>
<pre cla... | 5,280,444 | 489,400 | 2025-08-24 19:14:52 | 4,038,991 | 3,670 | 2010-10-28 01:16:25 | 135,965 | 2022-02-24 18:26:00 | https://stackoverflow.com/q/4037939 | https://stackoverflow.com/a/4038991 | <p>If you're using <a href="https://en.wikipedia.org/wiki/Windows_Server_2008" rel="noreferrer">Windows Server 2008</a> R2 then there is an <em>x64</em> and <em>x86</em> version of PowerShell both of which have to have their execution policies set. Did you set the execution policy on both hosts?</p>
<p>As an <em>Admini... | <p>If you're using <a href="https://en.wikipedia.org/wiki/Windows_Server_2008" rel="noreferrer">Windows Server 2008</a> R2 then there is an <em>x64</em> and <em>x86</em> version of PowerShell both of which have to have their execution policies set. Did you set the execution policy on both hosts?</p> <p>As an <em>Admini... | 526, 36466 | powershell, windows-server-2008-r2 | <h1>PowerShell says "execution of scripts is disabled on this system."</h1>
<p>I am trying to run a <code>cmd</code> file that calls a PowerShell script from <code>cmd.exe</code>, but I am getting this error:</p>
<blockquote>
<p><code>Management_Install.ps1</code> cannot be loaded because the execution of scripts is di... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 31 | bash | # PowerShell says "execution of scripts is disabled on this system."
I am trying to run a `cmd` file that calls a PowerShell script from `cmd.exe`, but I am getting this error:
> `Management_Install.ps1` cannot be loaded because the execution of scripts is disabled on this system.
I ran this command:
```
Set-Execut... | If you're using [Windows Server 2008](https://en.wikipedia.org/wiki/Windows_Server_2008) R2 then there is an *x64* and *x86* version of PowerShell both of which have to have their execution policies set. Did you set the execution policy on both hosts?
As an *Administrator*, you can set the execution policy by typing t... |
5410757 | How can I delete all lines that contain a specific string from a text file? | 2,416 | 2011-03-23 19:46:07 | <p>How would I use sed to delete all lines in a text file that contain a specific string?</p>
| 2,684,037 | 667,236 | 2025-12-13 14:13:19 | 5,410,784 | 3,649 | 2011-03-23 19:48:46 | 207,248 | 2025-12-12 05:23:22 | https://stackoverflow.com/q/5410757 | https://stackoverflow.com/a/5410784 | <p>To remove the line and print the output to standard out:</p>
<pre><code>sed '/pattern to match/d' ./infile
</code></pre>
<p>To directly modify the file (it does not work with BSD sed):</p>
<pre><code>sed -i '/pattern to match/d' ./infile
</code></pre>
<p>The same, but for BSD sed (Mac OS X and FreeBSD. It does not w... | <p>To remove the line and print the output to standard out:</p> <pre><code>sed '/pattern to match/d' ./infile </code></pre> <p>To directly modify the file (it does not work with BSD sed):</p> <pre><code>sed -i '/pattern to match/d' ./infile </code></pre> <p>The same, but for BSD sed (Mac OS X and FreeBSD. It does not w... | 390, 5282, 12189, 13401 | in-place, sed, shell, text-parsing | <h1>How can I delete all lines that contain a specific string from a text file?</h1>
<p>How would I use sed to delete all lines in a text file that contain a specific string?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 32 | bash | # How can I delete all lines that contain a specific string from a text file?
How would I use sed to delete all lines in a text file that contain a specific string? | To remove the line and print the output to standard out:
```
sed '/pattern to match/d' ./infile
```
To directly modify the file (it does not work with BSD sed):
```
sed -i '/pattern to match/d' ./infile
```
The same, but for BSD sed (Mac OS X and FreeBSD. It does not work with GNU sed):
```
sed -i '' '/pattern to ... |
8880603 | Loop through an array of strings in Bash? | 2,420 | 2012-01-16 13:21:16 | <p>I want to write a script that loops through 15 strings (array possibly?) Is that possible?</p>
<pre><code>for databaseName in listOfNames
then
# Do something
end
</code></pre>
| 2,293,789 | 218,183 | 2025-11-19 13:31:32 | 8,880,633 | 3,621 | 2012-01-16 13:24:47 | 548,225 | 2025-11-19 13:31:32 | https://stackoverflow.com/q/8880603 | https://stackoverflow.com/a/8880633 | <pre><code>## declare an array variable
declare -a arr=("element 1" "element 2" "element 3")
## loop through above array (quotes are important if your elements may contain spaces)
for i in "${arr[@]}"
do
echo "$i"
# or do whatever with individual element of array... | <pre><code>## declare an array variable declare -a arr=("element 1" "element 2" "element 3") ## loop through above array (quotes are important if your elements may contain spaces) for i in "${arr[@]}" do echo "$i" # or do whatever with individual element of array... | 114, 387, 390 | arrays, bash, shell | <h1>Loop through an array of strings in Bash?</h1>
<p>I want to write a script that loops through 15 strings (array possibly?) Is that possible?</p>
<pre><code>for databaseName in listOfNames
then
# Do something
end
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 33 | bash | # Loop through an array of strings in Bash?
I want to write a script that loops through 15 strings (array possibly?) Is that possible?
```
for databaseName in listOfNames
then
# Do something
end
``` | ```
## declare an array variable
declare -a arr=("element 1" "element 2" "element 3")
## loop through above array (quotes are important if your elements may contain spaces)
for i in "${arr[@]}"
do
echo "$i"
# or do whatever with individual element of array
done
# You can access them using echo "${arr[0]}", "${a... |
2518127 | How to reload .bashrc settings without logging out and back in again? | 2,268 | 2010-03-25 17:58:36 | <p>If I make changes to <code>.bashrc</code>, how do I reload it without logging out and back in?</p>
| 1,888,242 | 292,553 | 2024-09-06 14:44:36 | 2,518,150 | 3,583 | 2010-03-25 18:01:04 | 245,602 | 2020-10-21 14:18:32 | https://stackoverflow.com/q/2518127 | https://stackoverflow.com/a/2518150 | <p>You can enter the long form command:</p>
<pre><code>source ~/.bashrc
</code></pre>
<p>or you can use the shorter version of the command:</p>
<pre><code>. ~/.bashrc
</code></pre>
| <p>You can enter the long form command:</p> <pre><code>source ~/.bashrc </code></pre> <p>or you can use the shorter version of the command:</p> <pre><code>. ~/.bashrc </code></pre> | 387, 390, 391, 403, 12126 | bash, profile, reload, shell, terminal | <h1>How to reload .bashrc settings without logging out and back in again?</h1>
<p>If I make changes to <code>.bashrc</code>, how do I reload it without logging out and back in?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 34 | bash | # How to reload .bashrc settings without logging out and back in again?
If I make changes to `.bashrc`, how do I reload it without logging out and back in? | You can enter the long form command:
```
source ~/.bashrc
```
or you can use the shorter version of the command:
```
. ~/.bashrc
``` |
3601515 | How to check if a variable is set in Bash | 2,518 | 2010-08-30 14:54:38 | <p>How do I know if a variable is set in Bash?</p>
<p>For example, how do I check if the user gave the first parameter to a function?</p>
<pre><code>function a {
# if $1 is set ?
}
</code></pre>
| 2,489,781 | 260,127 | 2024-01-11 07:53:29 | 13,864,829 | 3,468 | 2012-12-13 17:04:53 | 1,633,643 | 2021-12-06 18:12:01 | https://stackoverflow.com/q/3601515 | https://stackoverflow.com/a/13864829 | <h2>(Usually) The right way</h2>
<pre><code>if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi
</code></pre>
<p>where <code>${var+x}</code> is a <a href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02" rel="noreferrer">parameter ... | <h2>(Usually) The right way</h2> <pre><code>if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi </code></pre> <p>where <code>${var+x}</code> is a <a href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02" rel="noreferrer">parameter ... | 276, 387, 390 | bash, shell, variables | <h1>How to check if a variable is set in Bash</h1>
<p>How do I know if a variable is set in Bash?</p>
<p>For example, how do I check if the user gave the first parameter to a function?</p>
<pre><code>function a {
# if $1 is set ?
}
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 35 | bash | # How to check if a variable is set in Bash
How do I know if a variable is set in Bash?
For example, how do I check if the user gave the first parameter to a function?
```
function a {
# if $1 is set ?
}
``` | ## (Usually) The right way
```
if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi
```
where `${var+x}` is a [parameter expansion](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02) which evaluates to nothing if `var` is unset, and substitutes the str... |
6482377 | Check existence of input argument in a Bash shell script | 2,049 | 2011-06-26 05:49:21 | <p>I need to check the existence of an input argument. I have the following script</p>
<pre><code>if [ "$1" -gt "-1" ]
then echo hi
fi
</code></pre>
<p>I get</p>
<pre><code>[: : integer expression expected
</code></pre>
<p>How do I check the input argument1 first to see if it exists?</p>
| 2,126,764 | 775,187 | 2024-06-03 04:03:01 | 6,482,403 | 3,395 | 2011-06-26 05:55:41 | 702,361 | 2021-01-28 08:38:46 | https://stackoverflow.com/q/6482377 | https://stackoverflow.com/a/6482403 | <p>It is:</p>
<pre class="lang-bash prettyprint-override"><code>if [ $# -eq 0 ]
then
echo "No arguments supplied"
fi
</code></pre>
<p>The <code>$#</code> variable will tell you the number of input arguments the script was passed.</p>
<p>Or you can check if an argument is an empty string or not like:</p>... | <p>It is:</p> <pre class="lang-bash prettyprint-override"><code>if [ $# -eq 0 ] then echo "No arguments supplied" fi </code></pre> <p>The <code>$#</code> variable will tell you the number of input arguments the script was passed.</p> <p>Or you can check if an argument is an empty string or not like:</p>... | 387, 390 | bash, shell | <h1>Check existence of input argument in a Bash shell script</h1>
<p>I need to check the existence of an input argument. I have the following script</p>
<pre><code>if [ "$1" -gt "-1" ]
then echo hi
fi
</code></pre>
<p>I get</p>
<pre><code>[: : integer expression expected
</code></pre>
<p>How do I check the input ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 36 | bash | # Check existence of input argument in a Bash shell script
I need to check the existence of an input argument. I have the following script
```
if [ "$1" -gt "-1" ]
then echo hi
fi
```
I get
```
[: : integer expression expected
```
How do I check the input argument1 first to see if it exists? | It is:
```
if [ $# -eq 0 ]
then
echo "No arguments supplied"
fi
```
The `$#` variable will tell you the number of input arguments the script was passed.
Or you can check if an argument is an empty string or not like:
```
if [ -z "$1" ]
then
echo "No argument supplied"
fi
```
The `-z` switch will test i... |
1358540 | How can I count all the lines of code in a directory recursively? | 2,114 | 2009-08-31 17:42:20 | <p>We've got a PHP application and want to count all the lines of code under a specific directory and its subdirectories.</p>
<p>We don't need to ignore comments, as we're just trying to get a rough idea.</p>
<pre><code>wc -l *.php
</code></pre>
<p>That command works great for a given directory, but it ignores subdire... | 1,285,868 | 77,413 | 2024-08-01 03:57:59 | 1,358,573 | 3,342 | 2009-08-31 17:50:12 | 76,794 | 2021-05-27 09:50:00 | https://stackoverflow.com/q/1358540 | https://stackoverflow.com/a/1358573 | <p><strong>Try:</strong></p>
<pre><code>find . -name '*.php' | xargs wc -l
</code></pre>
<p>or (when file names include special characters such as spaces)</p>
<pre><code>find . -name '*.php' | sed 's/.*/"&"/' | xargs wc -l
</code></pre>
<p><strong><a href="https://dwheeler.com/sloccount/" rel="noreferrer... | <p><strong>Try:</strong></p> <pre><code>find . -name '*.php' | xargs wc -l </code></pre> <p>or (when file names include special characters such as spaces)</p> <pre><code>find . -name '*.php' | sed 's/.*/"&"/' | xargs wc -l </code></pre> <p><strong><a href="https://dwheeler.com/sloccount/" rel="noreferrer... | 387, 390 | bash, shell | <h1>How can I count all the lines of code in a directory recursively?</h1>
<p>We've got a PHP application and want to count all the lines of code under a specific directory and its subdirectories.</p>
<p>We don't need to ignore comments, as we're just trying to get a rough idea.</p>
<pre><code>wc -l *.php
</code></pre... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 37 | bash | # How can I count all the lines of code in a directory recursively?
We've got a PHP application and want to count all the lines of code under a specific directory and its subdirectories.
We don't need to ignore comments, as we're just trying to get a rough idea.
```
wc -l *.php
```
That command works great for a gi... | **Try:**
```
find . -name '*.php' | xargs wc -l
```
or (when file names include special characters such as spaces)
```
find . -name '*.php' | sed 's/.*/"&"/' | xargs wc -l
```
**[The SLOCCount tool](https://dwheeler.com/sloccount/)** may help as well.
It will give an accurate source lines of code count for whatev... |
4651437 | How do I set a variable to the output of a command in Bash? | 2,507 | 2011-01-10 20:58:02 | <p>I have a pretty simple script that is something like the following:</p>
<pre><code>#!/bin/bash
VAR1="$1"
MOREF='sudo run command against $VAR1 | grep name | cut -c7-'
echo $MOREF
</code></pre>
<p>When I run this script from the command line and pass it the arguments, I am not getting any output. However, when I... | 3,105,029 | 570,402 | 2025-09-19 06:29:46 | 4,651,495 | 3,283 | 2011-01-10 21:04:18 | 8,454 | 2024-08-26 16:01:57 | https://stackoverflow.com/q/4651437 | https://stackoverflow.com/a/4651495 | <p>In addition to backticks <code>`command`</code>, <a href="http://www.gnu.org/software/bash/manual/bashref.html#Command-Substitution" rel="noreferrer">command substitution</a> can be done with <code>$(command)</code> or <code>"$(command)"</code>, which I find easier to read, and allows for nesting.</p>
<pre... | <p>In addition to backticks <code>`command`</code>, <a href="http://www.gnu.org/software/bash/manual/bashref.html#Command-Substitution" rel="noreferrer">command substitution</a> can be done with <code>$(command)</code> or <code>"$(command)"</code>, which I find easier to read, and allows for nesting.</p> <pre... | 387, 390, 1231 | bash, command-line, shell | <h1>How do I set a variable to the output of a command in Bash?</h1>
<p>I have a pretty simple script that is something like the following:</p>
<pre><code>#!/bin/bash
VAR1="$1"
MOREF='sudo run command against $VAR1 | grep name | cut -c7-'
echo $MOREF
</code></pre>
<p>When I run this script from the command line and... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 38 | bash | # How do I set a variable to the output of a command in Bash?
I have a pretty simple script that is something like the following:
```
#!/bin/bash
VAR1="$1"
MOREF='sudo run command against $VAR1 | grep name | cut -c7-'
echo $MOREF
```
When I run this script from the command line and pass it the arguments, I am not ... | In addition to backticks `` `command` ``, [command substitution](http://www.gnu.org/software/bash/manual/bashref.html#Command-Substitution) can be done with `$(command)` or `"$(command)"`, which I find easier to read, and allows for nesting.
```
OUTPUT="$(ls -1)"
echo "${OUTPUT}"
MULTILINE="$(ls \
-1)"
echo "${MUL... |
2264428 | How to convert a string to lower case in Bash | 1,893 | 2010-02-15 07:02:56 | <p>Is there a way in <a href="/questions/tagged/bash" class="post-tag" title="show questions tagged 'bash'" rel="tag">bash</a> to convert a string into a lower case string?</p>
<p>For example, if I have:</p>
<pre><code>a="Hi all"
</code></pre>
<p>I want to convert it to:</p>
<pre><code>"hi all"
</code></pre... | 1,602,361 | 266,008 | 2024-10-02 06:03:31 | 2,264,537 | 3,129 | 2010-02-15 07:43:20 | 131,527 | 2024-10-02 06:03:31 | https://stackoverflow.com/q/2264428 | https://stackoverflow.com/a/2264537 | <p>There are various ways:</p>
<h3><a href="https://wikipedia.org/wiki/POSIX" rel="noreferrer">POSIX standard</a></h3>
<h4><a href="https://wikipedia.org/wiki/Tr_%28Unix%29" rel="noreferrer">tr</a></h4>
<pre><code>$ echo "$a" | tr '[:upper:]' '[:lower:]'
hi all
</code></pre>
<h4><a href="https://wikipedia.org... | <p>There are various ways:</p> <h3><a href="https://wikipedia.org/wiki/POSIX" rel="noreferrer">POSIX standard</a></h3> <h4><a href="https://wikipedia.org/wiki/Tr_%28Unix%29" rel="noreferrer">tr</a></h4> <pre><code>$ echo "$a" | tr '[:upper:]' '[:lower:]' hi all </code></pre> <h4><a href="https://wikipedia.org... | 139, 387, 390, 9848 | bash, lowercase, shell, string | <h1>How to convert a string to lower case in Bash</h1>
<p>Is there a way in <a href="/questions/tagged/bash" class="post-tag" title="show questions tagged 'bash'" rel="tag">bash</a> to convert a string into a lower case string?</p>
<p>For example, if I have:</p>
<pre><code>a="Hi all"
</code></pre>
<p>I want ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 39 | bash | # How to convert a string to lower case in Bash
Is there a way in [bash](/questions/tagged/bash "show questions tagged 'bash'") to convert a string into a lower case string?
For example, if I have:
```
a="Hi all"
```
I want to convert it to:
```
"hi all"
``` | There are various ways:
### [POSIX standard](https://wikipedia.org/wiki/POSIX)
#### [tr](https://wikipedia.org/wiki/Tr_%28Unix%29)
```
$ echo "$a" | tr '[:upper:]' '[:lower:]'
hi all
```
#### [AWK](https://wikipedia.org/wiki/AWK)
```
$ echo "$a" | awk '{print tolower($0)}'
hi all
```
## Non-POSIX
You may run int... |
1521462 | Looping through the content of a file in Bash | 2,202 | 2009-10-05 17:52:54 | <p>How do I iterate through each line of a text file with <a href="https://en.wikipedia.org/wiki/Bash_(Unix_shell)" rel="noreferrer">Bash</a>?</p>
<p>With this script:</p>
<pre><code>echo "Start!"
for p in (peptides.txt)
do
echo "${p}"
done
</code></pre>
<p>I get this output on the screen:</p>
<pre><code>Start!... | 3,042,183 | 63,550 | 2025-12-03 13:38:30 | 1,521,498 | 3,056 | 2009-10-05 18:00:20 | 6,918 | 2019-10-31 17:28:04 | https://stackoverflow.com/q/1521462 | https://stackoverflow.com/a/1521498 | <p>One way to do it is:</p>
<pre><code>while read p; do
echo "$p"
done <peptides.txt
</code></pre>
<p>As pointed out in the comments, this has the side effects of trimming leading whitespace, interpreting backslash sequences, and skipping the last line if it's missing a terminating linefeed. If these are concern... | <p>One way to do it is:</p> <pre><code>while read p; do echo "$p" done <peptides.txt </code></pre> <p>As pointed out in the comments, this has the side effects of trimming leading whitespace, interpreting backslash sequences, and skipping the last line if it's missing a terminating linefeed. If these are concern... | 34, 58, 345, 387, 10327 | bash, io, linux, sh, unix | <h1>Looping through the content of a file in Bash</h1>
<p>How do I iterate through each line of a text file with <a href="https://en.wikipedia.org/wiki/Bash_(Unix_shell)" rel="noreferrer">Bash</a>?</p>
<p>With this script:</p>
<pre><code>echo "Start!"
for p in (peptides.txt)
do
echo "${p}"
done
</code></pre>
<p>... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 40 | bash | # Looping through the content of a file in Bash
How do I iterate through each line of a text file with [Bash](https://en.wikipedia.org/wiki/Bash_(Unix_shell))?
With this script:
```
echo "Start!"
for p in (peptides.txt)
do
echo "${p}"
done
```
I get this output on the screen:
```
Start!
./runPep.sh: line 3: sy... | One way to do it is:
```
while read p; do
echo "$p"
done <peptides.txt
```
As pointed out in the comments, this has the side effects of trimming leading whitespace, interpreting backslash sequences, and skipping the last line if it's missing a terminating linefeed. If these are concerns, you can do:
```
while IFS=... |
7131670 | Make a Bash alias that takes a parameter? | 1,899 | 2011-08-20 12:11:41 | <p>I used to use CShell (<a href="/questions/tagged/csh" class="post-tag" title="show questions tagged 'csh'" rel="tag">csh</a>), which lets you make an alias that takes a parameter. The notation was something like</p>
<pre><code>alias junk="mv \\!* ~/.Trash"
</code></pre>
<p>In Bash, this does not seem to wo... | 997,593 | 902,361 | 2025-02-04 10:19:27 | 7,131,683 | 2,996 | 2011-08-20 12:15:04 | 203,454 | 2019-04-11 08:24:04 | https://stackoverflow.com/q/7131670 | https://stackoverflow.com/a/7131683 | <p>Bash alias does not directly accept parameters. You will have to create a function.</p>
<p><code>alias</code> does not accept parameters but a function can be called just like an alias. For example:</p>
<pre><code>myfunction() {
#do things with parameters like $1 such as
mv "$1" "$1.bak"
cp "$2" "$1"
}... | <p>Bash alias does not directly accept parameters. You will have to create a function.</p> <p><code>alias</code> does not accept parameters but a function can be called just like an alias. For example:</p> <pre><code>myfunction() { #do things with parameters like $1 such as mv "$1" "$1.bak" cp "$2" "$1" }... | 387, 1448 | alias, bash | <h1>Make a Bash alias that takes a parameter?</h1>
<p>I used to use CShell (<a href="/questions/tagged/csh" class="post-tag" title="show questions tagged 'csh'" rel="tag">csh</a>), which lets you make an alias that takes a parameter. The notation was something like</p>
<pre><code>alias junk="mv \\!* ~/.Trash"
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 41 | bash | # Make a Bash alias that takes a parameter?
I used to use CShell ([csh](/questions/tagged/csh "show questions tagged 'csh'")), which lets you make an alias that takes a parameter. The notation was something like
```
alias junk="mv \\!* ~/.Trash"
```
In Bash, this does not seem to work. Given that Bash has a multitud... | Bash alias does not directly accept parameters. You will have to create a function.
`alias` does not accept parameters but a function can be called just like an alias. For example:
```
myfunction() {
#do things with parameters like $1 such as
mv "$1" "$1.bak"
cp "$2" "$1"
}
myfunction old.conf new.conf ... |
876239 | How to redirect and append both standard output and standard error to a file with Bash | 2,110 | 2009-05-18 04:19:45 | <p>To redirect <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29" rel="noreferrer">standard output</a> to a truncated file in Bash, I know to use:</p>
<pre><code>cmd > file.txt
</code></pre>
<p>To redirect standard output in Bash, appending to a file, I know to use:</p>
<pre><code>... | 1,166,671 | 63,051 | 2023-11-19 09:42:16 | 876,242 | 2,670 | 2009-05-18 04:23:16 | 95,810 | 2017-03-09 14:55:58 | https://stackoverflow.com/q/876239 | https://stackoverflow.com/a/876242 | <pre><code>cmd >>file.txt 2>&1
</code></pre>
<p>Bash executes the redirects from left to right as follows:</p>
<ol>
<li><code>>>file.txt</code>: Open <code>file.txt</code> in append mode and redirect <code>stdout</code> there.</li>
<li><code>2>&1</code>: Redirect <code>stderr</code> to <em>"... | <pre><code>cmd >>file.txt 2>&1 </code></pre> <p>Bash executes the redirects from left to right as follows:</p> <ol> <li><code>>>file.txt</code>: Open <code>file.txt</code> in append mode and redirect <code>stdout</code> there.</li> <li><code>2>&1</code>: Redirect <code>stderr</code> to <em>"... | 387, 4867, 6051, 19156, 26698 | append, bash, io-redirection, stderr, stdout | <h1>How to redirect and append both standard output and standard error to a file with Bash</h1>
<p>To redirect <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29" rel="noreferrer">standard output</a> to a truncated file in Bash, I know to use:</p>
<pre><code>cmd > file.txt
</code></... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 42 | bash | # How to redirect and append both standard output and standard error to a file with Bash
To redirect [standard output](https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29) to a truncated file in Bash, I know to use:
```
cmd > file.txt
```
To redirect standard output in Bash, appending to a fi... | ```
cmd >>file.txt 2>&1
```
Bash executes the redirects from left to right as follows:
1. `>>file.txt`: Open `file.txt` in append mode and redirect `stdout` there.
2. `2>&1`: Redirect `stderr` to *"where `stdout` is currently going"*. In this case, that is a file opened in append mode. In other words, the `&1` reuses... |
2013547 | Assigning default values to shell variables with a single command in bash | 1,467 | 2010-01-06 14:29:31 | <p>I have a whole bunch of tests on variables in a bash (3.00) shell script where if the variable is not set, then it assigns a default, e.g.:</p>
<pre><code>if [ -z "${VARIABLE}" ]; then
FOO='default'
else
FOO=${VARIABLE}
fi
</code></pre>
<p>I seem to recall there's some syntax to doing this in one line, s... | 984,074 | 87,408 | 2025-12-05 15:39:20 | 2,013,589 | 2,619 | 2010-01-06 14:36:56 | 241,774 | 2024-10-17 09:37:22 | https://stackoverflow.com/q/2013547 | https://stackoverflow.com/a/2013589 | <p>Very close to what you posted, actually. You can use something called <a href="https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html" rel="noreferrer">Bash parameter expansion</a> to accomplish this.</p>
<p>To get the assigned value, or <code>default</code> if it's missing:</p>
<pre><code... | <p>Very close to what you posted, actually. You can use something called <a href="https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html" rel="noreferrer">Bash parameter expansion</a> to accomplish this.</p> <p>To get the assigned value, or <code>default</code> if it's missing:</p> <pre><code... | 387, 390 | bash, shell | <h1>Assigning default values to shell variables with a single command in bash</h1>
<p>I have a whole bunch of tests on variables in a bash (3.00) shell script where if the variable is not set, then it assigns a default, e.g.:</p>
<pre><code>if [ -z "${VARIABLE}" ]; then
FOO='default'
else
FOO=${VARIABLE}
fi
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 43 | bash | # Assigning default values to shell variables with a single command in bash
I have a whole bunch of tests on variables in a bash (3.00) shell script where if the variable is not set, then it assigns a default, e.g.:
```
if [ -z "${VARIABLE}" ]; then
FOO='default'
else
FOO=${VARIABLE}
fi
```
I seem to recal... | Very close to what you posted, actually. You can use something called [Bash parameter expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html) to accomplish this.
To get the assigned value, or `default` if it's missing:
```
FOO="${VARIABLE:-default}" # FOO will be assigned 'defau... |
3137094 | Count number of lines in a non binary file (Like a CSV or a TXT) file in terminal | 1,458 | 2010-06-29 00:31:31 | <p>I have a text file, and I like to know the total number of line withou opening it. My document is like these, and I want to know how many lines actually...</p>
<pre><code>09:16:39 AM all 2.00 0.00 4.00 0.00 0.00 0.00 0.00 0.00 94.00
09:16:40 AM all 5.00 0.00 0.00 4.00 0.00 ... | 1,924,090 | 368,453 | 2024-09-13 12:33:01 | 3,137,099 | 2,601 | 2010-06-29 00:33:38 | 85,509 | 2015-04-29 19:27:45 | https://stackoverflow.com/q/3137094 | https://stackoverflow.com/a/3137099 | <p>Use <code>wc</code>:</p>
<pre><code>wc -l <filename>
</code></pre>
<p>This will output the number of lines in <code><filename></code>:</p>
<pre><code>$ wc -l /dir/file.txt
3272485 /dir/file.txt
</code></pre>
<p>Or, to omit the <code><filename></code> from the result use <code>wc -l < <fil... | <p>Use <code>wc</code>:</p> <pre><code>wc -l <filename> </code></pre> <p>This will output the number of lines in <code><filename></code>:</p> <pre><code>$ wc -l /dir/file.txt 3272485 /dir/file.txt </code></pre> <p>Or, to omit the <code><filename></code> from the result use <code>wc -l < <fil... | 58, 387, 531, 1231 | bash, command-line, linux, scripting | <h1>Count number of lines in a non binary file (Like a CSV or a TXT) file in terminal</h1>
<p>I have a text file, and I like to know the total number of line withou opening it. My document is like these, and I want to know how many lines actually...</p>
<pre><code>09:16:39 AM all 2.00 0.00 4.00 0.00 0.0... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 44 | bash | # Count number of lines in a non binary file (Like a CSV or a TXT) file in terminal
I have a text file, and I like to know the total number of line withou opening it. My document is like these, and I want to know how many lines actually...
```
09:16:39 AM all 2.00 0.00 4.00 0.00 0.00 0.00 0.00 ... | Use `wc`:
```
wc -l <filename>
```
This will output the number of lines in `<filename>`:
```
$ wc -l /dir/file.txt
3272485 /dir/file.txt
```
Or, to omit the `<filename>` from the result use `wc -l < <filename>`:
```
$ wc -l < /dir/file.txt
3272485
```
You can also pipe data to `wc` as well:
```
$ cat /dir/file.t... |
169511 | How do I iterate over a range of numbers defined by variables in Bash? | 2,273 | 2008-10-04 01:38:43 | <p>How do I iterate over a range of numbers in Bash when the range is given by a variable?</p>
<p>I know I can do this (called "sequence expression" in the Bash <a href="http://www.gnu.org/software/bash/manual/bashref.html#Brace-Expansion" rel="noreferrer">documentation</a>):</p>
<pre><code>for i in {1..5}; d... | 1,926,914 | 24,923 | 2024-10-05 16:49:03 | 169,517 | 2,507 | 2008-10-04 01:41:55 | 2,908 | 2016-04-23 00:41:06 | https://stackoverflow.com/q/169511 | https://stackoverflow.com/a/169517 | <pre><code>for i in $(seq 1 $END); do echo $i; done</code></pre>
<p>edit: I prefer <code>seq</code> over the other methods because I can actually remember it ;)</p>
| <pre><code>for i in $(seq 1 $END); do echo $i; done</code></pre> <p>edit: I prefer <code>seq</code> over the other methods because I can actually remember it ;)</p> | 367, 387, 390, 2531 | bash, for-loop, shell, syntax | <h1>How do I iterate over a range of numbers defined by variables in Bash?</h1>
<p>How do I iterate over a range of numbers in Bash when the range is given by a variable?</p>
<p>I know I can do this (called "sequence expression" in the Bash <a href="http://www.gnu.org/software/bash/manual/bashref.html#Brace-E... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 45 | bash | # How do I iterate over a range of numbers defined by variables in Bash?
How do I iterate over a range of numbers in Bash when the range is given by a variable?
I know I can do this (called "sequence expression" in the Bash [documentation](http://www.gnu.org/software/bash/manual/bashref.html#Brace-Expansion)):
```
f... | ```
for i in $(seq 1 $END); do echo $i; done
```
edit: I prefer `seq` over the other methods because I can actually remember it ;) |
1401482 | YYYY-MM-DD format date in shell script | 1,617 | 2009-09-09 19:06:56 | <p>I tried using <code>$(date)</code> in my bash shell script, however, I want the date in <code>YYYY-MM-DD</code> format.<br>
How do I get this?</p>
| 2,304,731 | 45,730 | 2024-08-06 13:04:41 | 1,401,495 | 2,406 | 2009-09-09 19:08:57 | 11,123 | 2024-08-06 13:04:41 | https://stackoverflow.com/q/1401482 | https://stackoverflow.com/a/1401495 | <p>In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external <code>date</code> (usually GNU date). Note that invoking a subshell has performance problems in Cygwin due to a slow <code>fork()</code> call on Windows.</p>
<p>As such:</p>
<pre><code># put current da... | <p>In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external <code>date</code> (usually GNU date). Note that invoking a subshell has performance problems in Cygwin due to a slow <code>fork()</code> call on Windows.</p> <p>As such:</p> <pre><code># put current da... | 387, 390, 5002, 10823, 35771 | bash, date, date-formatting, shell, strftime | <h1>YYYY-MM-DD format date in shell script</h1>
<p>I tried using <code>$(date)</code> in my bash shell script, however, I want the date in <code>YYYY-MM-DD</code> format.<br>
How do I get this?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 46 | bash | # YYYY-MM-DD format date in shell script
I tried using `$(date)` in my bash shell script, however, I want the date in `YYYY-MM-DD` format.
How do I get this? | In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external `date` (usually GNU date). Note that invoking a subshell has performance problems in Cygwin due to a slow `fork()` call on Windows.
As such:
```
# put current date as yyyy-mm-dd in $date
# -1 -> explicit c... |
6212219 | Passing parameters to a Bash function | 1,578 | 2011-06-02 08:35:17 | <p>I am trying to search how to pass parameters in a Bash function, but what comes up is always how to pass parameter from the <em>command line</em>.</p>
<p>I would like to pass parameters within my script. I tried:</p>
<pre><code>myBackupFunction("..", "...", "xx")
function myBackupFunct... | 2,039,197 | 445,543 | 2024-11-20 15:20:36 | 6,212,408 | 2,399 | 2011-06-02 08:57:02 | 7,412 | 2020-12-18 16:27:37 | https://stackoverflow.com/q/6212219 | https://stackoverflow.com/a/6212408 | <p>There are two typical ways of declaring a function. I prefer the second approach.</p>
<pre><code>function function_name {
command...
}
</code></pre>
<p>or</p>
<pre><code>function_name () {
command...
}
</code></pre>
<p>To call a function with arguments:</p>
<pre><code>function_name "$arg1" "$a... | <p>There are two typical ways of declaring a function. I prefer the second approach.</p> <pre><code>function function_name { command... } </code></pre> <p>or</p> <pre><code>function_name () { command... } </code></pre> <p>To call a function with arguments:</p> <pre><code>function_name "$arg1" "$a... | 360, 387, 2313, 5569 | arguments, bash, function, parameters | <h1>Passing parameters to a Bash function</h1>
<p>I am trying to search how to pass parameters in a Bash function, but what comes up is always how to pass parameter from the <em>command line</em>.</p>
<p>I would like to pass parameters within my script. I tried:</p>
<pre><code>myBackupFunction("..", "...... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 47 | bash | # Passing parameters to a Bash function
I am trying to search how to pass parameters in a Bash function, but what comes up is always how to pass parameter from the *command line*.
I would like to pass parameters within my script. I tried:
```
myBackupFunction("..", "...", "xx")
function myBackupFunction($directory,... | There are two typical ways of declaring a function. I prefer the second approach.
```
function function_name {
command...
}
```
or
```
function_name () {
command...
}
```
To call a function with arguments:
```
function_name "$arg1" "$arg2"
```
The function refers to passed arguments by their position (not b... |
13210880 | Replace one substring for another string in shell script | 1,457 | 2012-11-03 16:01:23 | <p>I have "I love Suzi and Marry" and I want to change "Suzi" to "Sara".</p>
<pre><code>firstString="I love Suzi and Marry"
secondString="Sara"
</code></pre>
<p>Desired result:</p>
<pre><code>firstString="I love Sara and Marry"
</code></pre>
| 1,824,557 | 1,796,726 | 2024-06-17 13:39:36 | 13,210,909 | 2,391 | 2012-11-03 16:05:06 | 978,917 | 2024-06-17 13:39:36 | https://stackoverflow.com/q/13210880 | https://stackoverflow.com/a/13210909 | <p>To replace the <em>first</em> occurrence of a pattern with a given string, use <code>${<em>parameter</em>/<em>pattern</em>/<em>string</em>}</code>:</p>
<pre><code>#!/bin/bash
firstString="I love Suzi and Marry"
secondString="Sara"
echo "${firstString/Suzi/"$secondString"}"
# p... | <p>To replace the <em>first</em> occurrence of a pattern with a given string, use <code>${<em>parameter</em>/<em>pattern</em>/<em>string</em>}</code>:</p> <pre><code>#!/bin/bash firstString="I love Suzi and Marry" secondString="Sara" echo "${firstString/Suzi/"$secondString"}" # p... | 387, 390 | bash, shell | <h1>Replace one substring for another string in shell script</h1>
<p>I have "I love Suzi and Marry" and I want to change "Suzi" to "Sara".</p>
<pre><code>firstString="I love Suzi and Marry"
secondString="Sara"
</code></pre>
<p>Desired result:</p>
<pre><code>firstString=... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 48 | bash | # Replace one substring for another string in shell script
I have "I love Suzi and Marry" and I want to change "Suzi" to "Sara".
```
firstString="I love Suzi and Marry"
secondString="Sara"
```
Desired result:
```
firstString="I love Sara and Marry"
``` | To replace the *first* occurrence of a pattern with a given string, use `${parameter/pattern/string}`:
```
#!/bin/bash
firstString="I love Suzi and Marry"
secondString="Sara"
echo "${firstString/Suzi/"$secondString"}"
# prints 'I love Sara and Marry'
```
To replace *all* occurrences, use `${parameter//pattern/string}... |
418896 | How to redirect output to a file and stdout | 1,677 | 2009-01-07 01:45:42 | <p>In bash, calling <code>foo</code> would display any output from that command on the stdout.</p>
<p>Calling <code>foo > output</code> would redirect any output from that command to the file specified (in this case 'output').</p>
<p>Is there a way to redirect output to a file <em>and</em> have it display on stdou... | 1,246,622 | 1,666 | 2024-03-19 09:17:37 | 418,899 | 2,378 | 2009-01-07 01:48:08 | 20,267 | 2017-10-23 17:10:56 | https://stackoverflow.com/q/418896 | https://stackoverflow.com/a/418899 | <p>The command you want is named <strong><a href="http://www.gnu.org/software/coreutils/manual/html_node/tee-invocation.html" rel="noreferrer"><code>tee</code></a></strong>:</p>
<pre><code>foo | tee output.file
</code></pre>
<p>For example, if you only care about stdout:</p>
<pre><code>ls -a | tee output.file
</code... | <p>The command you want is named <strong><a href="http://www.gnu.org/software/coreutils/manual/html_node/tee-invocation.html" rel="noreferrer"><code>tee</code></a></strong>:</p> <pre><code>foo | tee output.file </code></pre> <p>For example, if you only care about stdout:</p> <pre><code>ls -a | tee output.file </code... | 58, 345, 387, 724, 4867 | bash, file-io, io, linux, stdout | <h1>How to redirect output to a file and stdout</h1>
<p>In bash, calling <code>foo</code> would display any output from that command on the stdout.</p>
<p>Calling <code>foo > output</code> would redirect any output from that command to the file specified (in this case 'output').</p>
<p>Is there a way to redirect o... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 49 | bash | # How to redirect output to a file and stdout
In bash, calling `foo` would display any output from that command on the stdout.
Calling `foo > output` would redirect any output from that command to the file specified (in this case 'output').
Is there a way to redirect output to a file *and* have it display on stdout? | The command you want is named **[`tee`](http://www.gnu.org/software/coreutils/manual/html_node/tee-invocation.html)**:
```
foo | tee output.file
```
For example, if you only care about stdout:
```
ls -a | tee output.file
```
If you want to include stderr, do:
```
program [arguments...] 2>&1 | tee outfile
```
`2>&... |
4608187 | How to reload .bash_profile from the command line | 1,234 | 2011-01-05 19:09:07 | <p>How can I reload file <a href="https://en.wikipedia.org/wiki/Bash_(Unix_shell)#Legacy-compatible_Bash_startup_example" rel="noreferrer">.bash_profile</a> from the <em>command line</em>?</p>
<p>I can get the shell to recognize changes to <em>.bash_profile</em> by exiting and logging back in, but I would like to be ab... | 1,217,536 | 97,101 | 2024-10-08 02:19:42 | 4,608,197 | 2,292 | 2011-01-05 19:10:03 | 207,248 | 2024-10-08 02:19:42 | https://stackoverflow.com/q/4608187 | https://stackoverflow.com/a/4608197 | <p>Simply type <code>source ~/.bash_profile</code></p>
<p>Alternatively, if you like saving keystrokes, you can type <code>. ~/.bash_profile</code></p>
| <p>Simply type <code>source ~/.bash_profile</code></p> <p>Alternatively, if you like saving keystrokes, you can type <code>. ~/.bash_profile</code></p> | 387, 390, 1231 | bash, command-line, shell | <h1>How to reload .bash_profile from the command line</h1>
<p>How can I reload file <a href="https://en.wikipedia.org/wiki/Bash_(Unix_shell)#Legacy-compatible_Bash_startup_example" rel="noreferrer">.bash_profile</a> from the <em>command line</em>?</p>
<p>I can get the shell to recognize changes to <em>.bash_profile</em... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 50 | bash | # How to reload .bash_profile from the command line
How can I reload file [.bash_profile](https://en.wikipedia.org/wiki/Bash_(Unix_shell)#Legacy-compatible_Bash_startup_example) from the *command line*?
I can get the shell to recognize changes to *.bash_profile* by exiting and logging back in, but I would like to be ... | Simply type `source ~/.bash_profile`
Alternatively, if you like saving keystrokes, you can type `. ~/.bash_profile` |
343646 | Ignoring directories in Git repositories on Windows | 1,592 | 2008-12-05 12:17:28 | <p>How can I ignore directories or folders in Git using msysgit on Windows?</p>
| 2,050,509 | 43,603 | 2025-05-29 14:10:31 | 343,734 | 2,241 | 2008-12-05 12:54:10 | 43,613 | 2019-11-14 13:48:32 | https://stackoverflow.com/q/343646 | https://stackoverflow.com/a/343734 | <p>Create a file named <code>.gitignore</code> in your project's directory. Ignore directories by entering the directory name into the file (with a slash appended):</p>
<pre><code>dir_to_ignore/
</code></pre>
<p>More information is <a href="http://git-scm.com/docs/gitignore" rel="noreferrer">here</a>.</p>
| <p>Create a file named <code>.gitignore</code> in your project's directory. Ignore directories by entering the directory name into the file (with a slash appended):</p> <pre><code>dir_to_ignore/ </code></pre> <p>More information is <a href="http://git-scm.com/docs/gitignore" rel="noreferrer">here</a>.</p> | 64, 119, 21628, 25056, 61874 | git, git-bash, gitignore, msysgit, windows | <h1>Ignoring directories in Git repositories on Windows</h1>
<p>How can I ignore directories or folders in Git using msysgit on Windows?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 51 | bash | # Ignoring directories in Git repositories on Windows
How can I ignore directories or folders in Git using msysgit on Windows? | Create a file named `.gitignore` in your project's directory. Ignore directories by entering the directory name into the file (with a slash appended):
```
dir_to_ignore/
```
More information is [here](http://git-scm.com/docs/gitignore). |
2990414 | echo that outputs to stderr | 1,686 | 2010-06-07 14:36:16 | <p>Is there a standard Bash command that acts like <code>echo</code> but outputs to stderr rather than stdout?</p>
<p>I know I can do <code>echo foo 1>&2</code> but it's kinda ugly and, I suspect, error-prone (e.g. more likely to get edited wrong when things change).</p>
| 1,048,664 | 1,343 | 2023-10-10 06:11:19 | 23,550,347 | 2,201 | 2014-05-08 18:59:47 | 675,584 | 2023-05-09 22:29:35 | https://stackoverflow.com/q/2990414 | https://stackoverflow.com/a/23550347 | <p>You could do this, which facilitates reading:</p>
<pre><code>>&2 echo "error"
</code></pre>
<p><code>>&2</code> copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was <s... | <p>You could do this, which facilitates reading:</p> <pre><code>>&2 echo "error" </code></pre> <p><code>>&2</code> copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was <s... | 387 | bash | <h1>echo that outputs to stderr</h1>
<p>Is there a standard Bash command that acts like <code>echo</code> but outputs to stderr rather than stdout?</p>
<p>I know I can do <code>echo foo 1>&2</code> but it's kinda ugly and, I suspect, error-prone (e.g. more likely to get edited wrong when things change).</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 52 | bash | # echo that outputs to stderr
Is there a standard Bash command that acts like `echo` but outputs to stderr rather than stdout?
I know I can do `echo foo 1>&2` but it's kinda ugly and, I suspect, error-prone (e.g. more likely to get edited wrong when things change). | You could do this, which facilitates reading:
```
>&2 echo "error"
```
`>&2` copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was **originally** referring to. For more information see the [Bas... |
226703 | How do I prompt for Yes/No/Cancel input in a Linux shell script? | 1,921 | 2008-10-22 17:03:22 | <p>I want to pause input in a shell script, and prompt the user for choices.<br>
The standard <code>Yes</code>, <code>No</code>, or <code>Cancel</code> type question.<br>
How do I accomplish this in a typical bash prompt?</p>
| 1,415,315 | 9,084 | 2026-01-06 20:54:44 | 226,724 | 2,092 | 2008-10-22 17:08:50 | 9,084 | 2025-03-18 14:21:37 | https://stackoverflow.com/q/226703 | https://stackoverflow.com/a/226724 | <p>A widely available method to get user input at a shell prompt is the <a href="https://www.gnu.org/software/bash/manual/bashref.html#index-read" rel="noreferrer"><code>read</code></a> command. Here is a demonstration:</p>
<pre><code>while true; do
read -p "Do you wish to install this program? " yn
c... | <p>A widely available method to get user input at a shell prompt is the <a href="https://www.gnu.org/software/bash/manual/bashref.html#index-read" rel="noreferrer"><code>read</code></a> command. Here is a demonstration:</p> <pre><code>while true; do read -p "Do you wish to install this program? " yn c... | 58, 387, 390, 531 | bash, linux, scripting, shell | <h1>How do I prompt for Yes/No/Cancel input in a Linux shell script?</h1>
<p>I want to pause input in a shell script, and prompt the user for choices.<br>
The standard <code>Yes</code>, <code>No</code>, or <code>Cancel</code> type question.<br>
How do I accomplish this in a typical bash prompt?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 53 | bash | # How do I prompt for Yes/No/Cancel input in a Linux shell script?
I want to pause input in a shell script, and prompt the user for choices.
The standard `Yes`, `No`, or `Cancel` type question.
How do I accomplish this in a typical bash prompt? | A widely available method to get user input at a shell prompt is the [`read`](https://www.gnu.org/software/bash/manual/bashref.html#index-read) command. Here is a demonstration:
```
while true; do
read -p "Do you wish to install this program? " yn
case $yn in
[Yy]* ) make install; break;;
[Nn]*... |
4824590 | Propagate all arguments in a Bash shell script | 1,291 | 2011-01-28 03:34:04 | <p>I am writing a very simple script that calls another script, and I need to propagate the parameters from my current script to the script I am executing.</p>
<p>For instance, my script name is <code>foo.sh</code> and calls <code>bar.sh</code>.</p>
<p>foo.sh:</p>
<pre><code>bar $1 $2 $3 $4
</code></pre>
<p>How can I d... | 737,326 | 121,112 | 2026-01-14 22:40:28 | 4,824,637 | 2,024 | 2011-01-28 03:42:43 | 401,390 | 2026-01-14 22:40:28 | https://stackoverflow.com/q/4824590 | https://stackoverflow.com/a/4824637 | <p>Use <code>"$@"</code> instead of plain <code>$@</code> if you actually wish your parameters to be passed exactly as is.</p>
<p>Observe:</p>
<pre class="lang-bash prettyprint-override"><code>$ cat no_quotes.sh
#!/bin/bash
./echo_args.sh $@
$ cat quotes.sh
#!/bin/bash
./echo_args.sh "$@"
$ cat ec... | <p>Use <code>"$@"</code> instead of plain <code>$@</code> if you actually wish your parameters to be passed exactly as is.</p> <p>Observe:</p> <pre class="lang-bash prettyprint-override"><code>$ cat no_quotes.sh #!/bin/bash ./echo_args.sh $@ $ cat quotes.sh #!/bin/bash ./echo_args.sh "$@" $ cat ec... | 387, 31134 | bash, command-line-arguments | <h1>Propagate all arguments in a Bash shell script</h1>
<p>I am writing a very simple script that calls another script, and I need to propagate the parameters from my current script to the script I am executing.</p>
<p>For instance, my script name is <code>foo.sh</code> and calls <code>bar.sh</code>.</p>
<p>foo.sh:</p>... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 54 | bash | # Propagate all arguments in a Bash shell script
I am writing a very simple script that calls another script, and I need to propagate the parameters from my current script to the script I am executing.
For instance, my script name is `foo.sh` and calls `bar.sh`.
foo.sh:
```
bar $1 $2 $3 $4
```
How can I do this wi... | Use `"$@"` instead of plain `$@` if you actually wish your parameters to be passed exactly as is.
Observe:
```
$ cat no_quotes.sh
#!/bin/bash
./echo_args.sh $@
$ cat quotes.sh
#!/bin/bash
./echo_args.sh "$@"
$ cat echo_args.sh
#!/bin/bash
echo Received: $1
echo Received: $2
echo Received: $3
echo Received: $4
$ ./... |
255898 | How to iterate over arguments in a Bash script | 1,205 | 2008-11-01 18:14:21 | <p>I have a complex command that I'd like to make a shell/bash script of. I can write it in terms of <code>$1</code> easily:</p>
<pre><code>foo $1 args -o $1.ext
</code></pre>
<p>I want to be able to pass multiple input names to the script. What's the right way to do it? </p>
<p>And, of course, I want to handle fi... | 968,520 | 12,874 | 2023-07-31 17:02:04 | 255,913 | 2,010 | 2008-11-01 18:25:27 | 25,222 | 2023-07-31 17:02:04 | https://stackoverflow.com/q/255898 | https://stackoverflow.com/a/255913 | <p>Use <code>"$@"</code> to represent all the arguments:</p>
<pre><code>for var in "$@"
do
echo "$var"
done
</code></pre>
<p>This will iterate over each argument and print it out on a separate line. $@ behaves like $* except that, when quoted, the arguments are broken up properly if t... | <p>Use <code>"$@"</code> to represent all the arguments:</p> <pre><code>for var in "$@" do echo "$var" done </code></pre> <p>This will iterate over each argument and print it out on a separate line. $@ behaves like $* except that, when quoted, the arguments are broken up properly if t... | 387, 1231 | bash, command-line | <h1>How to iterate over arguments in a Bash script</h1>
<p>I have a complex command that I'd like to make a shell/bash script of. I can write it in terms of <code>$1</code> easily:</p>
<pre><code>foo $1 args -o $1.ext
</code></pre>
<p>I want to be able to pass multiple input names to the script. What's the right way... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 55 | bash | # How to iterate over arguments in a Bash script
I have a complex command that I'd like to make a shell/bash script of. I can write it in terms of `$1` easily:
```
foo $1 args -o $1.ext
```
I want to be able to pass multiple input names to the script. What's the right way to do it?
And, of course, I want to handle ... | Use `"$@"` to represent all the arguments:
```
for var in "$@"
do
echo "$var"
done
```
This will iterate over each argument and print it out on a separate line. $@ behaves like $* except that, when quoted, the arguments are broken up properly if there are spaces in them:
```
sh test.sh 1 2 '3 4'
1
2
3 4
``` |
1250079 | How to escape single quotes within single quoted strings | 1,494 | 2009-08-08 22:50:10 | <p>Let's say, you have a Bash <code>alias</code> like:</p>
<pre><code>alias rxvt='urxvt'
</code></pre>
<p>which works fine.</p>
<p>However:</p>
<pre class="lang-none prettyprint-override"><code>alias rxvt='urxvt -fg '#111111' -bg '#111111''
</code></pre>
<p>won't work, and neither will:</p>
<pre><code>alias rxvt=... | 813,241 | 152,404 | 2025-05-29 14:58:14 | 1,250,279 | 2,002 | 2009-08-09 00:52:37 | 42,610 | 2024-03-11 23:33:18 | https://stackoverflow.com/q/1250079 | https://stackoverflow.com/a/1250279 | <p>If you really want to use single quotes in the outermost layer, remember that you can glue both kinds of quotation. Example:</p>
<pre><code> alias rxvt='urxvt -fg '"'"'#111111'"'"' -bg '"'"'#111111'"'"
# ^^^^^ ^^^^^ ^^^^^ ^^^^
# ... | <p>If you really want to use single quotes in the outermost layer, remember that you can glue both kinds of quotation. Example:</p> <pre><code> alias rxvt='urxvt -fg '"'"'#111111'"'"' -bg '"'"'#111111'"'" # ^^^^^ ^^^^^ ^^^^^ ^^^^ # ... | 367, 387, 10804 | bash, quoting, syntax | <h1>How to escape single quotes within single quoted strings</h1>
<p>Let's say, you have a Bash <code>alias</code> like:</p>
<pre><code>alias rxvt='urxvt'
</code></pre>
<p>which works fine.</p>
<p>However:</p>
<pre class="lang-none prettyprint-override"><code>alias rxvt='urxvt -fg '#111111' -bg '#111111''
</code></... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 56 | bash | # How to escape single quotes within single quoted strings
Let's say, you have a Bash `alias` like:
```
alias rxvt='urxvt'
```
which works fine.
However:
```
alias rxvt='urxvt -fg '#111111' -bg '#111111''
```
won't work, and neither will:
```
alias rxvt='urxvt -fg \'#111111\' -bg \'#111111\''
```
So how do you ... | If you really want to use single quotes in the outermost layer, remember that you can glue both kinds of quotation. Example:
```
alias rxvt='urxvt -fg '"'"'#111111'"'"' -bg '"'"'#111111'"'"
# ^^^^^ ^^^^^ ^^^^^ ^^^^
# 12345 12345 12345 1234
```
... |
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