There are two files (for example called „f1” and „f2”). We want to swap contents of these files. Here is an easy bash script, which solves this problem:

#!/bin/sh
# Created by Wojtek Jamrozy (www.wojtekrj.net)
mv $1 cop_$1
mv $2 $1
mv cop_$1 $2

[download id=”8″]
Download this file or make a text file with this content named swap and make it executable with command

chmod +x swap

Then copy this file to /usr/local/bin directory using:

cp swap /usr/local/bin

If you have this file in /usr/local/bin directory (or any other included in $PATH environment variable – command

echo $PATH

will show other directories) you don’t have to write full path to script:

swap f1 f2

will swap contents of files f1 and f2.
Example of usage in shell:

wojtekrj@wojtek-laptop:~$ echo "File 1" > file1 && echo "File 2" > file2
wojtekrj@wojtek-laptop:~$ cat file1
File 1
wojtekrj@wojtek-laptop:~$ cat file2
File 2
wojtekrj@wojtek-laptop:~$ swap file1 file2
wojtekrj@wojtek-laptop:~$ cat file1
File 2
wojtekrj@wojtek-laptop:~$ cat file2
File 1

#!/bin/sh

is a standard header, which helps bash shell recognize file as a bash script.

mv file1 file2

a command, which rename/move file from path file1 to file2

cat file

show content of file

When the script is executed with two arguments (like in example – swap f1 f2), $1 will contain first argument – f1, and $2 second – f2.
When $1 or $2 appears in script, it’s replaced with content of $1 or $2:

mv $1 cop_$1 -> mv f1 cop_f1
mv $2 $1 -> mv f2 f1

echo text_to_display

echo "text_to_display"

commands will show text text_to_display

command > file

will save output of command to file file