What’s the difference between “man 3” command vs. “man” command?

fixit_fiona

I read in Wikipedia that man 3 is used in Linux in section 3 of the man pages. And section 3 refers to Library functions, covering in particular the C standard library. I tried man 3 ls and got this: No entry for ls in section 3 of the manual I wonder when to use man 3 and when to use man and do they serve difference purposes?

Originally asked by user2157668 on Stack Exchange (superuser) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

man 3 ls will only show you a man page for ls in section 3 of the manual. Section 3 covers library functions; since there's (probably) no library function named ls , it won't find anything. The man command without a section number searches the sections in a predefined order. On my Ubuntu 24.04 system, the default is " 1 n l 8 3 0 2 3type 3posix 3pm 3perl 3am 5 4 9 6 7 ". The order can be reconfigured. . So man ls will find the ls man page in section 1, which covers user commands. The sections (on my Ubuntu system) are: Executable programs or shell commands System calls (functions provided by the kernel) Library calls (functions within program libraries) Special files (usually found in /dev...

Full answer by Keith Thompson: https://superuser.stackexchange.com/a/581558 (CC BY-SA 4.0).

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