The Linux man-pages project

The Linux man-pages project documents the Linux kernel and C library interfaces that are employed by user-space programs. With respect to the C library, the primary focus is the GNU C library (glibc), although, where known, documentation of variations on other C libraries available for Linux is also included. The project provides manual pages in the following sections:

• 1: User commands; man-pages includes a very few Section 1 pages that document programs supplied by the GNU C library.
• 2: System calls documents the system calls provided by the Linux kernel.
• 3: Library functions documents the functions provided by the standard C library.
• 4: Devices documents details of various devices, most of which reside in /dev.
• 5: Files describes various file formats and filesystems, and includes proc(5), which documents the /proc file system.
• 7: Overviews, conventions, and miscellaneous.
• 8: Superuser and system administration commands; man-pages includes a very few Section 8 pages that document programs supplied by the GNU C library.

chmod
chown
df
fdisk
find
getent
gpasswwd
journalctl
parted
systemctl
useradd
usermod