The man in Linux

1. View the Help information for a command
Mans mkdir

2. View the Help information for the service configuration file
Mans Services

Description
A. If no man is installed by Yum install Man
B. If the command and service have the same name, specify clearly
1.Linux through Whereis xxx can see the command and Help document address of XXX
2. Help document if it is xxx.1.gz then xxx for the command
3. Help document if it is xxx.5.gz then xxx for service
4. When using man at this time can be added 1 or 5来 designation, for example: Man 5 xxx
C. Can only view commands that are not bash-level
D. If it is a bash-level command, use the Help command to view, for example: Help CD
E. What if the difference between a command is bash or non-bash?
# which CD
/usr/bin/which:no CD in (...)

# Man CD
NAME
Bash,:,., [, alias, BG, bind, break, BUILTIN, caller, CD, command, Compgen,
Complete, compopt, continue, declare, dirs, Disown, Echo, enable, eval, exec,
Exit, export, False, FC, FG, Getopts, hash, help, history, jobs, kill, let,
Local, logout, Mapfile, popd, printf, pushd, pwd, read, ReadOnly, return, set,
Shift, shopt, source, suspend, test, times, trap, true, type, typeset, Ulimit,
Umask, Unalias, unset, wait-bash built-in commands, see Bash (1)

The man in Linux