Fedora Linux

Writing Simple Scripts

bash command lines can get to be very long, especially when pipes are used. A script is a text file that contains shell commands that may itself be executed as a command, providing an easy way to reuse complex sequences of commands. In fact, bash provides a complete programming language for use in scripts.

How Do I Do That?

To create a script, simply place commands in a text file. For example, this script will display the ten largest files in the current directory:

ls -lS | tail -n +2 | head -10

Save this file as topten. In order to run the script, you will need to set read and execute permission:

$ chmod a+rx 
               
                  topten
               

The script can be executed by specifying the directory and filename (or an absolute pathname):

$ ./topten
-rw-r--r--  1 root root    807103 Jul 12 21:18 termcap
-rw-r--r--  1 root root    499861 Jul 17 08:08 prelink.cache
-rw-r--r--  1 root root    362031 Feb 23 08:09 services
-rw-r--r--  1 root root     97966 Jul 15 11:19 ld.so.cache
-rw-r--r--  1 root root     92794 Jul 12 12:46 Muttrc
-rw-r--r--  1 root root     83607 Mar 23 07:23 readahead.files
-rw-r--r--  1 root root     73946 Jul 13 02:23 sensors.conf
-rw-r--r--  1 root root     45083 Jul 12 18:33 php.ini
-rw-r--r--  1 root root     30460 Jul 13 20:36 jwhois.conf
-rw-r--r--  1 root root     26137 Mar 23 07:23 readahead.early.files

The directory name is required because the current directory (.) is not in the list of directories normally searched for commands (called the PATH). To make your script accessible to all users, move it to the ...