Linux/BASH: Difference between revisions

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* <pre>#!/bin/bash</pre>
* <pre>#!/bin/bash</pre>


== Output & Piping ==
* output to file
<pre>
command > file.txt            # redirect output
command >> file.txt            # append to file
command &> file.txt            # stdout and stderr to file
command &>> file.txt          # stdout and stderr append to file
command 2> file.txt            # stderr to file
command 2>> file.txt          # stderr append to file
command | tee -a file.txt      # stdout to terminal and file (append)
command |& tee -a file.txt    # stdout+stderr to terminal and file (append)
</pre>redirecting output<pre>
command 2>&1 >/dev/null        # stderr to stdout and stdout to null
</pre>
== If ==
== If ==
*
*
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   else command2
   else command2
fi
fi
</pre>
</pre><syntaxhighlight lang="bash">
if [ -f file.txt ]; then echo "file exists"; fi
</syntaxhighlight>


== For loop ==
<syntaxhighlight lang="bash">
for OUTPUT in $(linuxcommand)
do
command1 on $OUTPUT
command2 on $OUTPUT
commandN
done
</syntaxhighlight>


== Links ==
* https://devhints.io/bash
* http://tldp.org/LDP/abs/html/special-chars.html
* http://tldp.org/LDP/abs/html/special-chars.html
* http://tldp.org/LDP/abs/html/internalvariables.html
* http://tldp.org/LDP/abs/html/internalvariables.html

Latest revision as of 10:18, 21 January 2021

Shebang

  • #!/bin/bash

Output & Piping

  • output to file
command > file.txt             # redirect output
command >> file.txt            # append to file

command &> file.txt            # stdout and stderr to file
command &>> file.txt           # stdout and stderr append to file

command 2> file.txt            # stderr to file
command 2>> file.txt           # stderr append to file

command | tee -a file.txt      # stdout to terminal and file (append)
command |& tee -a file.txt     # stdout+stderr to terminal and file (append)

redirecting output

command 2>&1 >/dev/null # stderr to stdout and stdout to null

If

if [ condition ]
  then command1
  else command2
fi
if [ -f file.txt ]; then echo "file exists"; fi

For loop

for OUTPUT in $(linuxcommand)
do
	command1 on $OUTPUT
	command2 on $OUTPUT
	commandN
done

Links