One Order a Day - Order Help
How to learn a bash command systematically:
Requirements, understand the format of commands, options, help manuals, cases, exercises, extensions.
What effect do you want to achieve? Do you have such commands, the format and use of commands, what other options do you have, the complete help manual in the system, what are the commonly used options and cases, and the extended use of commands?
5w1h method: what,why,when,where,who,how,
1. Help documentation for the program itself: / usr/share/doc/cmd-version
2. Official Documents for Distribution: http://www.redhat.com/docs
3.Google Hack Search
4.slideshare slides: http://www.slideshare.net/
Typecmd // View command type, whether it belongs to bash internal or external commands, and shows the path
cmd --version or cmd -V // / View the version of the command tool
whatis // Display man help page and simple description
which // Display File Path
whereis // Find file binary, source, man help file path
hash // External Command Cache
help cmd or cmd --help // internal commands to help queries
info // Multi-page Display Command Help
man // Major Command Help Manual, Recommended Use
type
Is the type of display command internal or external?
Usage: type [-afptP] name [name ...] -a Display all attributes, including alias Alias, internal commands builtin Or external commands and list absolute paths -f Display whether the file type is internal or external, and show the path -P Capitalization P，Absolute path to display commands -t Display the type of command, internal builtin，alias alias，external file，Keyword retention keyword
[Execution of orders]#type -a ls
ls is aliased to `ls -p --color=auto'
ls is /usr/bin/ls
[Execution of orders]#type ll
ll is aliased to `ls -al --color=auto'
[Execution of orders]#type -a cd
cd is a shell builtin
cd is /usr/bin/cd
[Execution of orders]#type -a python
python is /usr/bin/python
[Execution of orders]#type -a cd ls pwd
cd is a shell builtin
cd is /usr/bin/cd
ls is aliased to `ls -p --color=auto'
ls is /usr/bin/ls
pwd is a shell builtin
pwd is /usr/bin/pwd
[Execution of orders]#type whatis
whatis is hashed (/usr/bin/whatis)
[Execution of orders]#type {
{ is a shell keyword
[Execution of orders]#type [
[ is a shell builtin
[Execution of orders]#type apachectl
apachectl is /app/apache25/bin/apachectlView the version of a command or software
[Execution of orders]#ls --version ls (GNU coreutils) 8.22 Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Written by Richard M. Stallman and David MacKenzie. [Execution of orders]#python -V Python 2.7.5
whatis
man Help Page and Function Description for Displaying Commands
Usage: whatis [OPTION...] KEYWORD... -r regular expression regex
[Execution of orders]#whatis ls ls (1) - list directory contents ls (1p) - list directory contents [Execution of orders]#whatis ll ll: nothing appropriate. [Execution of orders]#whatis cd cd (1) - bash built-in commands, see bash(1) cd (1p) - change the working directory [Execution of orders]#whatis python python (1) - an interpreted, interactive, object-oriented programming language [Execution of orders]#whatis -r pwd lckpwdf (3) - get shadow password file entry pwd (1) - print name of current/working directory pwd (1p) - return working directory name pwd.h (0p) - password structure pwdx (1) - report current working directory of a process ulckpwdf (3) - get shadow password file entry unix_chkpwd (8) - Helper binary that verifies the password of the current user
which
The absolute path of the display command is searched according to the directory set by PATH. Different users have different PATH, and the contents of the files they search are different.
Usage: /usr/bin/which [options] [--] COMMAND [...]
[Execution of orders]#which -a ls alias ls='ls -p --color=auto' /usr/bin/ls [Execution of orders]#which -a ll alias ll='ls -al --color=auto' /usr/bin/ls [Execution of orders]#which -a cd /usr/bin/cd [Execution of orders]#which -a python /usr/bin/python [Execution of orders]#which apachectl /app/apache25/bin/apachectl
whereis
Find the binary program, source code, man manual and other related file paths for the specified command
Usage: whereis [options] file -b Search only binary files -m Search only man manual -s Search source code
[Execution of orders]#whereis ls ls: /usr/bin/ls /usr/share/man/man1/ls.1.gz /usr/share/man/man1p/ls.1p.gz [Execution of orders]#whereis ll ll: [Execution of orders]#whereis cd cd: /usr/bin/cd /usr/share/man/man1/cd.1.gz /usr/share/man/man1p/cd.1p.gz [Execution of orders]#whereis python python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/share/man/man1/python.1.gz [Execution of orders]#whereis kernel kernel: /usr/lib/kernel /etc/kernel [Execution of orders]#whereis apachectl apachectl: /app/apache25/bin/apachectl
Internal Order Help [Execution of orders]#help pwd pwd: pwd [-LP] Print the name of the current working directory. Options: -L print the value of $PWD if it names the current working directory -P print the physical directory, without any symbolic links By default, `pwd' behaves as if `-L' were specified. Exit Status: Returns 0 unless an invalid option is given or the current directory cannot be read. //External command help [Execution of orders]#whatis --help Usage: whatis [OPTION...] KEYWORD... -d, --debug emit debugging messages -v, --verbose print verbose warning messages -r, --regex interpret each keyword as a regex -w, --wildcard the keyword(s) contain wildcards -l, --long do not trim output to terminal width -C, --config-file=FILE use this user configuration file -L, --locale=LOCALE define the locale for this search -m, --systems=SYSTEM use manual pages from other systems -M, --manpath=PATH set search path for manual pages to PATH -s, --sections=LIST, --section=LIST search only these sections (colon-separated) -?, --help give this help list --usage give a short usage message -V, --version print program version Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options. Report bugs to cjwatson@debian.org.
man Help Document
Man Storage Address: / usr/share/man
Configuration file for man command: c68: /etc/man.conf | c73: /etc/man_db.conf
man Chapter Classification: 1. User Command 2. System Call 3.C Library Call 4. Device File and Special File 5. Configuration File Format 6. Game 7. Miscellaneous 8. Management Command 9.Linux Kernel API
whatis passwd
man 1 passwd
man 5 passwd
man's display is implemented using less command, and so is the operation.
Downward flip: space, ^ V,^f, ^ F
Turn up the screen: b, ^ B
Turn down half screen: d, ^ D
Turn up half screen: u, ^ U
Turn up a row: Enter, ^ N, e, ^ E, j, ^ J
Turn down one line: y, ^ Y, ^ P, k, ^ K
Exit: q
Jump to line n:
Back to the beginning: 1G
Back to the end:G
Search down, case-insensitive: / keyword next n; last N
Search up, case-insensitive:? keyword next n; last N
The man cmd command helps export to files and retains the original format
man ls | col -b > ls.txt
Go to the manual page of the search command at the specified location and display: man-M/PATH CMD
#man -aw -M /usr/share/man/ passwd /usr/share/man/man1/passwd.1.gz /usr/share/man/man1/sslpasswd.1ssl.gz /usr/share/man/man5/passwd.5.gz #man -aw -M /usr/local/share/man/ passwd //Manual page entries without passwd // By default, only one layer of directory matches will be searched, and directory queries will not be recursive #man -aw -M /usr/local/share/man/zh_CN/ passwd /usr/local/share/man/zh_CN/man5/passwd.5 man -k password //List all man pages with matching keywords, using whatis database man -f passwd //Equivalent to whatis man -w [chapter]keyword //Print man help file path man -w 5 passwd
Other Help Documents: / usr/share/doc
Symbol Description: []: Optional Content <>: Required Content a|b: Two Choices...: The same Content can appear many times