How can I open "Linux Programmer's Manual" after having installed "POSIX Programmer's Manual"?
On Ubuntu 18.04 I usually see "Linux Programmer's Manual" by man command.
But I wanted to see "POSIX Programmer's Manual", so I installed the package "manpages-posix-dev" by below command.
apt install manpages-posix-dev
Now I could see "POSIX Programmer's Manual", but I couldn't see "Linux Programmer's Manual" anymore. I want to see "Linux Programmer's Manual" as well.
Consider, for example, you're interested in printf. You can search the manual using the apropos command. My version of that tool accepts a regular expression, so I'll use it to filter out other pages that include printf in the name. If yours doesn't support regular expressions, you can just use apropos printf and ignore entries that don't explicitly match what you're looking for:
$ apropos '^printf$'
printf (1) - format and print data
printf (1p) - write formatted output
printf (3) - formatted output conversion
printf (3p) - print formatted output
Notice in this case I get 4 results in the manual for things called printf. Each version has a number (or a number followed by a character) in parentheses. That number represents the "section" of the manual in which the corresponding is found.
Now consider that we're interested in the C library function printf. Section 3 of the manual is for library calls, so we'd be interested in one of the last two (or perhaps both). The one in section 3 is from the Linux Programmer's Manual; the one in section 3p is from the POSIX Programmer's Manual.
When you invoke the man command, you can optionally specify the section of the manual to read. If I want the man page for printf from the Linux Programmer's Manaual, I can do:
$ man 3 printf
PRINTF(3) Linux Programmer's Manual PRINTF(3)
...
Alternatively, if I want the man page for printf from the POSIX Programmer's Manual, I can do:
$ man 3p printf
PRINTF(3P) POSIX Programmer's Manual PRINTF(3P)
...
See man man for more information about the sections of the manual, and what type of information is found in each section:
The table below shows the section numbers of the manual followed by the types of pages they contain.
1 Executable programs or shell commands
2 System calls (functions provided by the kernel)
3 Library calls (functions within program libraries)
4 Special files (usually found in /dev)
5 File formats and conventions eg /etc/passwd
6 Games
7 Miscellaneous (including macro packages and conventions), e.g.man(7),groff(7)
8 System administration commands (usually only for root)
9 Kernel routines [Non standard]
Solved.
$ man -a [command name]