Linux and Unix Shell Programming

11.2. sort on the system

Sort can be used to sort the usernames from the /etc/passwd file. All we need to do is sort on field 1, which is the login name field, then pass the output using a pipe to awk, and let awk print the first field.

						$ cat passwd | sort -t: +0 | awk -F":" '{print $1}' 
adm 
bin 
daemon 
... 
...
					

Sort can also be used on the df command to print the usage column in desending order. Here’s a normal df output.

						$df 
Filesystem  1024-blocks Used   Available Capacity Mounted on 
/dev/hda5   495714      291027 179086    62%      / 
/dev/hda1   614672      558896 55776     91%      /dos
					

Now using -b option, which ignores any leading blanks when sorting, we use field 4 (+4), which is the ‘capacity’ column. Reversing the sort gives a clearer picture of the free space on ...