Guide to Unix/Commands/Getting Help

man Displays the manual page for the specified command A useful option is: $ man -k TEXT This searches manual page titles and synopsis lines for TEXT Examples: To display the manual page for the chown command: $ man chown man has different sections. section 1 is user commands section 2 is system calls (used by programs to communicate with the kernel) section 3 is library reference (for programming in C) section 4 is device drivers section 5 is configuration files and other file formats section 6 is games section 7 is miscellaneous (for example, "ascii" map and C "operator" precedence) section 8 is system commands (like user commands, but mostly for root) A section number can be specified before the page name. For example, man chmod normally shows the user command "chmod". To see the system call "chmod": $ man 2 chmod To search the man pages for "newsgroups", $ man -k newsgroups actsync (8) - synchronize newsgroupsoups newsgroups (1) - a program to list unsubscribed newsgroups If this does not work you may have to run the makewhatis command. Links: man, opengroup.org man man page, man.cat-v.org info An advanced man command that is sometimes available. It displays the improved manual pages in Info format for specified command. Seems absent from POSIX. Examples: To display the manual page for the grep command: $ info grep To find occurrence of 'grep' in all info manual pages: $ info --apropos grep "(autoconf-2.13)Examining Declarations" -- EGREP_CPP "(autoconf-2.13)Examining Declarations" -- EGREP_HEADER "(autoconf-2.13)Old Macro Names" -- HEADER_EGREP ... Some copies of info lack the "-w" option. To see the physical location of 'grep' info manual page: $ info -w grep /usr/share/info/grep.info.gz To view a file a info page: $ info -f ./some_cmd.info.gz Links: info man pag, freebsd.org info man page, manpages.ubuntu.com Stand-alone GNU Info 6.2 - GNU manual, gnu.org apropos Searches the manual page short descriptions for a specified keyword. Seems absent from POSIX. On many systems this is exactly the same as the -k option of the man command. Examples: $ apropos newsgroups active (5) - list of active Usenet newsgroups newsgroups (1) - a program to list unsubscribed newsgroups Links: apropos man page, freebsd.org whatis Displays short man page descriptions. Seems absent from POSIX. Examples: $ whatis info info (1) - read Info documents info (5) - readable online documentation $ whatis chmod chmod (1) - change file modes chmod, fchmod (2) - change mode of file Links: whatis man page, freebsd.org makewhatis Creates the database for the whatis, apropos, and man -k commands. This is commonly run automatically by your system however sometimes you need to run this manually. Seems absent from POSIX. Examples: # makewhatis $ sudo makewhatis Links: makewhatis man page, freebsd.org