less (Display Content with Pager)
The less command is functioning as a pager, which is used to read the contents of a text file one page(one screen) at a time.
Open a file with the less command
You can easily open the file with the less command.
less file_a
less command with pipe
less command is useful when the output of a command contains a large number of lines. For example, when you use the ls command with the -l option for a directory with multiple sub-directories and files, using the less command is helpful. The following is an example demonstrating a check of the list of contents of the /etc directory with its details.
ls -l /etc | less
You can see the result like the one below with : at the end. In this mode, you can scroll pages with keyboard actions.
total 796
drwxr-xr-x 3 root root 4096 Jul 16 2020 NetworkManager
drwxr-xr-x 2 root root 4096 Jul 16 2020 PackageKit
drwxr-xr-x 4 root root 4096 Jul 16 2020 X11
drwxr-xr-x 4 root root 4096 Jul 16 2020 acpi
-rw-r--r-- 1 root root 3028 Jul 16 2020 adduser.conf
drwxr-xr-x 2 root root 4096 Jul 16 2020 alternatives
drwxr-xr-x 3 root root 4096 Jul 16 2020 apparmor
drwxr-xr-x 7 root root 4096 Jul 16 2020 apparmor.d
drwxr-xr-x 3 root root 4096 Jul 16 2020 apport
drwxr-xr-x 7 root root 4096 Jul 16 2020 apt
-rw-r----- 1 root daemon 144 Nov 12 2018 at.deny
-rw-r--r-- 1 root root 2319 Feb 25 2020 bash.bashrc
:
Keyboard navigation
When you display file contents with the less command, you can use your keyboard to move around the document. Here are some frequently used keys.
- ↑ and ↓ arrow keys: move one line
- → and ← arrow keys: scroll horizontally
- space key: go to next page
- b key: go to previous page
- g key: jump to first line
- G key: jump last line
- q key: quit
Note: more command
There is another pager command called more. As the functionality of the more command is limited, using the less command for a pager gives a better user experience.
You can also learn this topic offline. Click 
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