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