Linux Command - less
The linux command less allows you to page through a text file.
This tool is similar to ‘more’ but it has a lot more features. It doesn’t need to read in an entire input file at one time so it starts faster with very large files when compared to other tools like vi.
There are more commands and options than what is shown here. We’re just covering the common / normally useful stuff. Multiple commands exist that do the same thing. There are many commands that behave in a very similar way. I’ve included a lot of redundant stuff but there exists a lot more in the man page.
Page through a file:
less /var/log/dpkg.log
Show line numbers:
less -N /var/log/dpkg.log
Searches will be case insensitive:
less -I /var/log/dpkg.log
Using a pipe:
ps -ef | less
Two files at once:
less /var/log/dpkg.log /var/log/boot.log
Commands
Commands can be proceeded by a number ( n ).
Common / Useful Commands
| q | quit |
| space | scroll forward n lines ( window size ) |
| enter | scroll forward 1 line |
| up/down arrow | up or down 1 line |
| left/right arrow | scroll left or right |
| b | scroll back n lines ( window size ) |
| g | go to first line |
| 5g | go to line 5 |
| G | End of file |
Searching
| /pattern | search for pattern (regex) |
| /!pattern | search for negated pattern |
| /?pattern | search backwards |
During a search:
| n | next match |
| N | previous match |
| ESC-u | turn on / off search highlighting |
| ESC-U | turn on / off search highlighting and clear pattern |
| &/pattern | only display matching lines ‘/’ added automatically |
Extra Commands
You probably won’t ever use most of these.
| f | scroll forward n lines ( window size ) |
| e | scroll forward 1 line |
| j | scroll forward 1 line |
| z | scroll forward n lines ( window size ) ( change default n value if specfied ) |
| d | scroll forward n lines ( half screen size ) ( change default n value for d/u if specfied ) |
| b | scroll back n lines ( window size ) |
| w | scroll back n lines ( window size )( change default n value if specfied ) |
| y k | scroll back 1 line |
| u | scroll back n lines ( half screen size ) ( change default n value for d/u if specfied ) |
| J | like j but keeps scrolling after end of file |
| K or Y | like k but keeps scrolling after beginning of file |
| F | scroll forward but keep reading at end of file ( kind of like “tail -F”) |
Files:
| :n | examine next file |
| :p | examine previous file |
| :x | examine firest file |
| :d | remove file from list |
More:
| = | info about file, includes line number of bottom line |
| - | apply a command line option while already running |
| – | same but for long option |
| v | edit this line with an editor |
| s | filename save to a file ( only when using piped input ) |
Matching and Jumping
| m | mark a line with whatever you single letter you type next ( displays when using -J ) |
| M | same but for last displayed line |
| ma | mark line with ‘a’ |
| ‘a | jump to line marked with ‘a’ |
| ’’ | jump back |
| ’^ | jump to end of file |
| ’$ | jump to beginning of file |
Options
| -N | display line numbers |
| -n | suppress line |
| -J | show status column |
| -i | ignore case for searches |
| -I | ignore case for searches even with uppercase pattern |
| -F | exit at end of file |
| -Q | silence the terminal bell |
| –save-marks | save marks for another session |