Unix Cheat Sheet (Unix Linux 命令行参考手册)

happmaoo · 发表于 2013-1-15 08:14:11

Unix Cheat Sheet

http://www.rain.org/~mkummel<wbr></wbr>/unix.html

People who use Windows without DOS, or a Macintosh, or PPP without a terminal, or an ISP's menu without the Unix prompt are at a disadvantage. Something is happening, and they don't know what it is. I like to know what's really going on, so I've been learning some Unix. The Net is a Unix place. I'm no wizard, but I'm comfortable with basic commands and occasionally type "rm" at my DOS prompt instead of "del". This is my Unix cheat sheet, so I can remember. Uppercase and lowercase matter. These commands (mostly) work with my C-shell account on RAIN. Your account might be different, especially if your prompt ends with a "$" (Korn shell) rather than a "%", so be cautious. When I need help, I reach for the books UNIX in a Nutshell (O'Reilly) and Unix Unbound by Harley Hahn (Osborne/McGraw Hill, 1994).
This page won't look right without table support. Most of this is available in a text version.

Help on any Unix command. RTFM!

man {command}

Type man ls to read the manual for the ls command.

man {command} > {filename}

Redirect help to a file to download.

whatis {command}

Give short description of command. (Not on RAIN?)

apropos {keyword}

Search for all Unix commands that match keyword, eg apropos file. (Not on RAIN?)

List a directory

ls {path}

It's ok to combine attributes, eg ls -laF gets a long listing of all files with types.

ls {path_1} {path_2}

List both {path_1} and {path_2}.

ls -l {path}

Long listing, with date, size and permisions.

ls -a {path}

Show all files, including important .dot files that don't otherwise show.

ls -F {path}

Show type of each file. "/" = directory, "*" = executable.

ls -R {path}

Recursive listing, with all subdirs.

ls {path} > {filename}

Redirect directory to a file.

ls {path} | more

Show listing one screen at a time.

dir {path}

Useful alias for DOS people, or use with ncftp.

Change to directory

cd {dirname}

There must be a space between.

cd ~

Go back to home directory, useful if you're lost.

cd ..

Go back one directory.

cdup

Useful alias, like "cd ..", or use with ncftp.

Make a new directory

mkdir {dirname}

Remove a directory

rmdir {dirname}

Only works if {dirname} is empty.

rm -r {dirname}

Remove all files and subdirs. Careful!

Print working directory

pwd

Show where you are as full path. Useful if you're lost or exploring.

Copy a file or directory

cp {file1} {file2}

cp -r {dir1} {dir2}

Recursive, copy directory and all subdirs.

cat {newfile} >> {oldfile}

Append newfile to end of oldfile.

Move (or rename) a file

mv {oldfile} {newfile}

Moving a file and renaming it are the same thing.

mv {oldname} {newname}

Delete a file

rm {filespec}

? and * wildcards work like DOS should. "?" is any character; "*" is any string of characters.

ls {filespec}
rm {filespec}

Good strategy: first list a group to make sure it's what's you think...
...then delete it all at once.

Download with zmodem

(Use sx with xmodem.)

sz [-a|b] {filename}

-a = ascii, -b = binary. Use binary for everything. (It's the default?)

sz *.zip

Handy after downloading with FTP. Go talk to your spouse while it does it's stuff.

Upload with zmodem

(Use rx with xmodem.)

rz [-a|b] (filename}

Give rz command in Unix, THEN start upload at home. Works fine with multiple files.

View a text file

more {filename}

View file one screen at a time.

less {filename}

Like more, with extra features.

cat {filename}

View file, but it scrolls.

cat {filename} | more

View file one screen at a time.

page {filename}

Very handy with ncftp.

pico {filename}

Use text editor and don't save.

Edit a text file.

pico {filename}

The same editor PINE uses, so you already know it. vi and emacs are also available.

Create a text file.

cat > {filename}

Enter your text (multiple lines with enter are ok) and press control-d to save.

pico {filename}

Create some text and save it.

Compare two files

diff {file1} {file2}

Show the differences.

sdiff {file1} {file2}

Show files side by side.

Other text commands

grep '{pattern}' {file}

Find regular expression in file.

sort {file1} > {file2}

Sort file1 and save as file2.

sort -o {file} {file}

Replace file with sorted version.

spell {file}

Display misspelled words.

wc {file}

Count words in file.

Find files on system

find {filespec}

Works with wildcards. Handy for snooping.

find {filespec} > {filename}

Redirect find list to file. Can be big!

Make an Alias

alias {name} '{command}'

Put the command in 'single quotes'. More useful in your .cshrc file.

Wildcards and Shortcuts

*

Match any string of characters, eg page* gets page1, page10, and page.txt.

?

Match any single character, eg page? gets page1 and page2, but not page10.

[...]

Match any characters in a range, eg page[1-3] gets page1, page2, and page3.

~

Short for your home directory, eg  cd ~ will take you home, and rm -r ~ will destroy it.

.

The current directory.

..

One directory up the tree, eg ls ...

Pipes and Redirection

(You pipe a command to another command, and redirect it to a file.)

{command} > {file}

Redirect output to a file, eg ls > list.txt writes directory to file.

{command} >> {file}

Append output to an existing file, eg cat update >> archive adds update to end of archive.

{command} < {file}

Get input from a file, eg sort < file.txt

{command} < {file1} > {file2}

Get input from file1, and write to file2, eg sort < old.txt > new.txt sorts old.txt and saves as new.txt.

{command} | {command}

Pipe one command to another, eg ls | more gets directory and sends it to more to show it one page at a time.

Permissions, important and tricky!

Unix permissions concern who can read a file or directory, write to it, and execute it. Permissions are granted or withheld with a magic 3-digit number. The three digits correspond to the owner (you); the group (?); and the world (everyone else). Think of each digit as a sum:

	execute permission	= 1
	write permission	= 2
	<!--D(["mb","write and execute (1+2)\u003c/td\>\u003ctd\>\u003d 3 \u003cbr\>\u003c/td\>\n\u003c/tr\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>read permission \u003c/td\>\u003ctd\>\u003d 4\u003cbr\>\u003c/td\>\n\u003c/tr\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>read and execute (4+1)\u003c/td\>\u003ctd\>\u003d 5\u003cbr\>\u003c/td\>\n\u003c/tr\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>read and write (4+2)\u003c/td\>\u003ctd\>\u003d 6\u003cbr\>\u003c/td\>\n\u003c/tr\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>read, write and execute (4+2+1)\u003c/td\>\u003ctd\>\u003d 7\u003cbr\>\u003c/td\>\n\u003c/tr\>\u003c/tbody\>\u003c/table\>\n\u003c/p\>\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd colspan\u003d\"2\"\>Add the number value of the permissions you want to grant each group to make a three digit number, \none digit each for the owner, the group, and the world. Here are some useful combinations. Try to figure them out!\u003cp\>\n\u003c/p\>\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod 600 {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>You can read and write; the world can&#39;t. Good for files.\u003cbr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod 700 {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>You can read, write, and execute; the world can&#39;t. Good for scripts.\u003cbr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod 644 {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>You can read and write; the world can only read. Good for web pages.\u003cbr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod 755 {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>You can read, write, and execute; the world can read and execute. Good for programs you want to share, and your \u003ctt\>public_html\u003c/tt\> directory.\u003cbr\>\n\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd colspan\u003d\"3\"\>\u003chr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd colspan\u003d\"3\"\>\u003cfont size\u003d\"+1\"\>Permissions, another way\u003c/font\>\u003cbr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd colspan\u003d\"2\"\>\nYou can also change file permissions with letters:\u003cp\>\n\u003ctable border\u003d\"0\" width\u003d\"400\"\>\n \u003ctbody\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>\u003cb\>u\u003c/b\> \u003d user (yourself) \u003c/td\>\u003ctd\>\u003cb\>g\u003c/b\> \u003d group \u003c/td\>\u003ctd\>\u003cb\>a\u003c/b\> \u003d everyone\u003cbr\>\u003c/td\>\n \u003c/tr\>\u003ctr\>\u003ctd width\u003d\"30\"\>\u003cbr\>\u003c/td\>\u003ctd\>\u003cb\>r\u003c/b\> \u003d read \u003c/td\>\u003ctd\>\u003cb\>w\u003c/b\> \u003d write \u003c/td\>\u003ctd\>\u003cb\>x\u003c/b\> \u003d execute\u003cbr\>\u003c/td\>\n\u003c/tr\>\u003c/tbody\>\u003c/table\>\n\u003c/p\>\u003cp\>\n\u003c/p\>\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod u+rw {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>Give yourself read and write permission\u003cbr\>\n\u003c/td\>\u003c/tr\>\u003ctr\>\u003ctd\>\u003cbr\>\u003c/td\>\u003ctd\>\u003ctt\>chmod u+x {filespec}\u003c/tt\>\u003c/td\>\u003ctd\>Give yourself execute permission.",1]);//--> write and execute (1+2)	= 3
	read permission	= 4
	read and execute (4+1)	= 5
	read and write (4+2)	= 6
	read, write and execute (4+2+1)	= 7

Add the number value of the permissions you want to grant each group to make a three digit number, one digit each for the owner, the group, and the world. Here are some useful combinations. Try to figure them out!

chmod 600 {filespec}

You can read and write; the world can't. Good for files.

chmod 700 {filespec}

You can read, write, and execute; the world can't. Good for scripts.

chmod 644 {filespec}

You can read and write; the world can only read. Good for web pages.

chmod 755 {filespec}

You can read, write, and execute; the world can read and execute. Good for programs you want to share, and your public_html directory.

Permissions, another way

You can also change file permissions with letters:

	u = user (yourself)	g = group	a = everyone
	r = read	w = write	x = execute

chmod u+rw {filespec}

Give yourself read and write permission

chmod u+x {filespec}

Give yourself execute permission.

chmod a+rw {filespec}

Give read and write permission to everyone.

Applications I use

finger {userid}

Find out what someone's up to.

gopher

Gopher.

irc

IRC, but not available on RAIN.

lynx

Text-based Web browser, fast and lean.

ncftp

Better FTP.

pico {filename}

Easy text editor, but limited. vi and emacs are available.

pine

Email.

telnet {host}

Start Telnet session to another host.

tin

Usenet.

uudecode {filename}
uuencode {filename}

Do it on the server to reduce download size about 1/3.

ytalk {userid}

Chat with someone else online, eg ytalk mkummel. Please use w first so you don't interrupt a big download!

System info

date

Show date and time.

df

Check system disk capacity.

du

Check your disk usage and show bytes in each directory.

more /etc/motd

Read message of the day, "motd" is a useful alias..

printenv

Show all environmental variables (in C-shell% - use set in Korn shell$).

quota -v

Check your total disk use.

uptime

Find out system load.

w

Who's online and what are they doing?

Unix Directory Format

Long listings (ls -l) have this format:

- file
d directory,                                           * executable
^ symbolic links (?)  file size (bytes) file name / directory
^          ^             ^                ^       ^

drwxr-xr-x 11 mkummel    2560 Mar  7 23:25 public_html/
-rw-r--r--  1 mkummel    10297 Mar  8 23:42 index.html
                                          ^
   ^^^       user permission  (rwx)    date and time last modified

      ^^^    group permission (rwx)
         ^^^  world permission (rwx)

How to Make an Alias

An alias lets you type something simple and do something complex.  It's a shorthand for a command. If you want to type "dir" instead of "ls -l" then type alias dir 'ls -l'.  The single quotes tell Unix that the enclosed text is one command. Aliases are more useful if they're permanent so you don't have to think about them. You can do this by  adding the alias to your .cshrc file so they're automatically loaded when you start. Type pico .cshrc and look for the alias section and add what you want. It will be effective when you start.  Just remember that if you make an alias with the name of a Unix command, that command will become unavailable.
Here are a few aliases from my .cshrc file:

         # enter your aliases here in the form:
# alias    this means this

         alias    h    history
         alias    m    more
         aliasqquota -v

         alias    bye    exit
         alias ls ls -F
         alias    dir    ls
         alias cdupcd ..
         aliasmotdmore /etc/motd

How to Make a Script

A Unix script is a text file of commands that can be executed, like a .bat file in DOS. Unix contains a powerful programming language with loops and variables that I don't really understand.  Here's a useful example. Unix can't rename a bunch of files at once the way DOS can. This is a problem if you develop Web pages on a DOS machine and then upload them to your Unix Server. You might have a bunch of .htm files that you want to rename as .html files,  but Unix makes you do it one by one. This is actually not a defect. (It's a feature!)  Unix is just being more consistent than DOS. So make a script!
Make a text file (eg with pico) with the following lines.  The first line is special. It tells Unix what program or shell should execute the script.  Other # lines are comments.
#! /bin/csh
# htm2html converts *.htm files to *.html
foreach f ( *.htm )
   set base=`basename $f .htm`
   mv $f $base.html
end
Save this in your home directory as htm2html (or whatever). Then make it user-executable by typing chmod 700 htm2html. After this a * will appear by the file name when you ls -F, to show that it's executable. Change to  a directory with .htm files and type ~/htm2html, and it will do its stuff. Think about scripts whenever you find yourself doing the same tedious thing over and over.

Dotfiles (aka Hidden Files)
<blockquote> Dotfile names begin with a "."  These files and directories don't show up when you list a directory unless you use the -a option, so they are also calledhidden files. Type ls -la in your home directory to see what you have.
Some of these dotfiles are crucial.  They initialize your shell and the programs you use, like autoexec.bat in DOS and .ini files in Windows.  rc means "run commands". These are all text files that can be edited, but change t

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