Less tricks in linux on the bash command line

Some tricks that is worth to know when working on the linux bash cli that can save you a lot of time.

1. To tell less to normal print the raw control character of your stream you can use the '-r' or '-R' options.

$ ls -la --color | less -X 
total 3284
drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 ESC[0mESC[01;34m.ESC[0m
drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ESC[01;34m..ESC[0m
drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 ESC[01;34m.adobeESC[0m
drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 ESC[01;34m.ankiESC[0m

$ ls -la --color | less -X -r
total 3284
drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 .
drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ..
drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 .adobe
drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 .anki

2. To list only #n lines from the input with or without the raw characters being interpreted.

$ ls -la --color | cat -t | head -10
total 3284
drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 ^[[0m^[[01;34m.^[[0m
drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ^[[01;34m..^[[0m
drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 ^[[01;34m.adobe^[[0m
drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 ^[[01;34m.anki^[[0m

$ ls -la --color | head -10
total 3284
drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 .
drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ..
drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 .adobe
drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 .anki

3. To list files with line numbers.

$ less -N -X /etc/init.d/networking 
      1 #!/bin/sh -e
      2 ### BEGIN INIT INFO
      3 # Provides:          networking
      4 # Required-Start:    

$ ls -la --color | cat -n -t | head -5
     1 total 3284
     2 drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 ^[[0m^[[01;34m.^[[0m
     3 drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ^[[01;34m..^[[0m
     4 drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 ^[[01;34m.adobe^[[0m
     5 drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 ^[[01;34m.anki^[[0m

$ ls -la --color | cat -n | head -5
     1 total 3284
     2 drwxr-xr-x 90 radoslaw radoslaw   4096 2011-04-24 10:22 .
     3 drwxr-xr-x  4 root     root       4096 2010-08-02 20:37 ..
     4 drwx------  5 radoslaw radoslaw   4096 2011-01-31 12:18 .adobe
     5 drwxr-xr-x  4 radoslaw radoslaw   4096 2009-11-07 20:53 .anki

Reference:

• less -R  
• Shell Script To Number Lines Of Files