The help command is the simplest way to get information regarding a built-in shell command. It helps you fetch information from the shell’s internal documentation.
Example
$ find --help
Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]
default path is the current directory; default expression is -print
expression may consist of: operators, options, tests, and actions:
operators (decreasing precedence; -and is implicit where no others are given):
( EXPR ) ! EXPR -not EXPR EXPR1 -a EXPR2 EXPR1 -and EXPR2
EXPR1 -o EXPR2 EXPR1 -or EXPR2 EXPR1 , EXPR2
positional options (always true): -daystart -follow -regextype
normal options (always true, specified before other expressions):
-depth --help -maxdepth LEVELS -mindepth LEVELS -mount -noleaf
--version -xautofs -xdev -ignore_readdir_race -noignore_readdir_race
tests (N can be +N or -N or N): -amin N -anewer FILE -atime N -cmin N
-cnewer FILE -ctime N -empty -false -fstype TYPE -gid N -group NAME
-ilname PATTERN -iname PATTERN -inum N -iwholename PATTERN -iregex PATTERN
-links N -lname PATTERN -mmin N -mtime N -name PATTERN -newer FILE
-nouser -nogroup -path PATTERN -perm [-/]MODE -regex PATTERN
-readable -writable -executable
-wholename PATTERN -size N[bcwkMG] -true -type [bcdpflsD] -uid N
-used N -user NAME -xtype [bcdpfls]
-context CONTEXT
actions: -delete -print0 -printf FORMAT -fprintf FILE FORMAT -print
-fprint0 FILE -fprint FILE -ls -fls FILE -prune -quit
-exec COMMAND ; -exec COMMAND {} + -ok COMMAND ;
-execdir COMMAND ; -execdir COMMAND {} + -okdir COMMAND ;
Report (and track progress on fixing) bugs via the findutils bug-reporting
page at http://savannah.gnu.org/ or, if you have no web access, by sending
email to <bug-findutils@gnu.org>.
$ man [COMMAND NAME]...
man command in Linux is used to display the user manual of any command that we can run on the terminal. It provides a detailed view of the command which includes NAME, SYNOPSIS, DESCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUES, ERRORS, FILES, VERSIONS, EXAMPLES, AUTHORS and SEE ALSO.