Linux commands: man

Every time I don’t know how to use a command, I type man <command> to get the manual:

This is a man page, short for manual. Man pages are an essential tool to learn as a developer. Every command in this course has one, and it’s always there, even on a server with no internet access.

They contain so much information that sometimes it’s almost too much. The screenshot above is just 1 of 14 screens of explanation for the ls command.

Man pages open inside a pager, the same program less uses. Press the space bar to go forward one screen, b to go back, / followed by a word to search, and q to quit. That last one matters: beginners often get stuck inside a man page.

Try it now:

man ls

Type /hidden and press enter, and the pager jumps to the first place where the word appears. That’s how I find the option I need without reading all 14 screens.

Man pages are divided into 8 different sections, identified by a number:

• 1 is user commands
• 2 is kernel system calls
• 3 is C library functions
• 4 is devices
• 5 is files formats and filesystems
• 6 is games
• 7 is miscellaneous commands, conventions and overviews
• 8 is superuser and system administrator commands

The number matters when the same name lives in more than one section. passwd is both a command (section 1) and a file format (section 5). man passwd opens the command. To read about the file, you ask for the section explicitly:

man 5 passwd

If you ask for something that has no manual, man says so:

No manual entry for tldrx

Either you typed the name wrong, or the tool doesn’t ship a man page. Many modern tools print help with --help instead.

Most of the times when I need to learn a command quickly I use this site called tldr pages: https://tldr.sh/. It’s a command you can install, then you run it like this: tldr <command>. It gives you a very quick overview of a command, with some handy examples of common usage scenarios:

This is not a substitute for man, but a handy tool to avoid losing yourself in the huge amount of information present in a man page. I start with tldr to find the common case, then open the man page when I need all the options and details.

The man command works on Linux, macOS, WSL, and anywhere you have a UNIX environment