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Bash Scripting
https://sushant747.gitbooks.io/total-oscp-guide/basics_of_linux.html
Iterate over a file
This script will iterate over a file and echo out every single line:
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#!/bin/bash
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for line in $(cat file.txt);do
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echo $line
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done
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Another way of writing is this:
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#!/bin/bash
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while read p; do
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echo $p
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done <file.txt
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For-loops
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#!/bin/bash
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for ((i = 0; i < 10; i++)); do
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echo $i
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done
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Another way to write this is by using the program
seq. Seq is pretty much like range() in python. So it can be used like this:1
#!/bin/bash
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for x in `seq 1 100`; do
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echo $x
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done
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If statement
$1 here represent the first argument.1
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if [ "$1" == "" ]; then
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echo "This happens"
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fi
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If/Else
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#!/bin/bash
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if [ "$1" == "" ]; then
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echo "This happens"
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else
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echo "Something else happens"
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fi
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Command line arguments
Command line arguments are represented like this
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#!/bin/bash
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$1
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This is the first command line argument.
Daemonize an execution
If you do a ping-sweep with host the command will take about a second to complete. And if you run that against 255 hosts I will take a long time to complete. To avoid this we can just deamonize every execution to make it faster. We use the
& to daemonize it.1
#!/bin/bash
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for ip in $(cat ips.txt); do
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ping -c 1 $ip &
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done
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Use the output of command
It has happened to me several times that I want to input the output of a command into a new command, for example:
I search for a file, find three, and take the last line, which is a path. Now I want to cat that path:
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#!/bin/bash
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locate 646.c | tail -n 1
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This can be done like this:
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#!/bin/bash
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cat $(locate 646.c | tail -n 1)
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Last modified 2yr ago