1、Unix Command SummarySee the Unix tutorial for a leisurely, self-paced introduction on how to use the commands listed below. For more documentation on a command, consult a good book, or use the man pages. For example, for more information on grep, use the command man grep.Contents cat - for creating
2、and displaying short files chmod - change permissions cd - change directory cp - for copying files date - display date echo - echo argument ftp - connect to a remote machine to download or upload files grep - search file head - display first part of file ls - see what files you have lpr - standard p
3、rint command (see also print ) more - use to read files mkdir - create directory mv - for moving and renaming files ncftp - especially good for downloading files via anonymous ftp. print - custom print command (see also lpr ) pwd - find out what directory you are in rm - remove a file rmdir - remove
4、 directory rsh - remote shell setenv - set an environment variable sort - sort file tail - display last part of file tar - create an archive, add or extract files telnet - log in to another machine wc - count characters, words, linescatThis is one of the most flexible Unix commands. We can use to cr
5、eate, view and concatenate files. For our first example we create a three-item English-Spanish dictionary in a file called “dict.“% cat dictred rojogreen verdeblue azul%stands for “hold the control key down, then tap d“. The symbol tells the computer that what is typed is to be put into the file dic
6、t. To view a file we use cat in a different way:% cat dictred rojogreen verdeblue azul%If we wish to add text to an existing file we do this:% cat dictwhite blancoblack negro%Now suppose that we have another file tmp that looks like this:% cat tmpcat gatodog perro%Then we can join dict and tmp like
7、this:% cat dict tmp dict2We could check the number of lines in the new file like this:% wc -l dict28The command wc counts things - the number of characters, words, and line in a file.chmodThis command is used to change the permissions of a file or directory. For example to make a file essay.001 read
8、able by everyone, we do this:% chmod a+r essay.001To make a file, e.g., a shell script mycommand executable, we do this% chmod +x mycommandNow we can run mycommand as a command.To check the permissions of a file, use ls -l . For more information on chmod, use man chmod.cdUse cd to change directory.
9、Use pwd to see what directory you are in.% cd english% pwd% /u/ma/jeremy/english% lsnovel poems% cd novel% pwd% /u/ma/jeremy/english/novel% lsch1 ch2 ch3 journal scrapbook% cd % pwd% /u/ma/jeremy/english% cd poems% cd% /u/ma/jeremyJeremy began in his home directory, then went to his english subdirec
10、tory. He listed this directory using ls , found that it contained two entries, both of which happen to be diretories. He cdd to the diretory novel, and found that he had gotten only as far as chapter 3 in his writing. Then he used cd to jump back one level. If had wanted to jump back one level, then
11、 go to poems he could have said cd /poems. Finally he used cd with no argument to jump back to his home directory.cpUse cp to copy files or directories.% cp foo foo.2This makes a copy of the file foo.% cp /poems/jabber .This copies the file jabber in the directory poems to the current directory. The
12、 symbol “.“ stands for the current directory. The symbol “ stands for the home directory.dateUse this command to check the date and time.% dateFri Jan 6 08:52:42 MST 1995echoThe echo command echoes its arguments. Here are some examples:% echo thisthis% echo $EDITOR/usr/local/bin/emacs% echo $PRINTER
13、b129lab1Things like PRINTER are so-called environment variables. This one stores the name of the default printer - the one that print jobs will go to unless you take some action to change things. The dollar sign before an environment variable is needed to get the value in the variable. Try the follo
14、wing to verify this:% echo PRINTERPRINTERftpUse ftp to connect to a remote machine, then upload or download files. See also: ncftpExample 1: Well connect to the machine , then change director to mystuff, then download the file homework11:% ftp solitudeConnected to .220 FTP server (Version wu-2.4(11
15、) Mon Apr 18 17:26:33 MDT 1994) ready.Name (solitude:carlson): jeremy331 Password required for jeremy.Password: 230 User jeremy logged in.ftp cd mystuff250 CWD command successful.ftp get homework11ftp quitExample 2: Well connect to the machine , then change director to mystuff, then upload the file
16、collected-letters:% ftp solitudeConnected to .220 FTP server (Version wu-2.4(11) Mon Apr 18 17:26:33 MDT 1994) ready.Name (solitude:carlson): jeremy331 Password required for jeremy.Password: 230 User jeremy logged in.ftp cd mystuff250 CWD command successful.ftp put collected-lettersftp quitThe ftp
17、program sends files in ascii (text) format unless you specify binary mode:ftp binaryftp put fooftp asciiftp get barThe file foo was transferred in binary mode, the file bar was transferred in ascii mode.grepUse this command to search for information in a file or files. For example, suppose that we h
18、ave a file dict whose contents arered rojogreen verdeblue azulwhite blancoblack negroThen we can look up items in our file like this;% grep red dictred rojo% grep blanco dictwhite blanco% grep brown dict%Notice that no output was returned by grep brown. This is because “brown“ is not in our dictiona
19、ry file.Grep can also be combined with other commands. For example, if one had a file of phone numbers named “ph“, one entry per line, then the following command would give an alphabetical list of all persons whose name contains the string “Fred“.% grep Fred ph | sortAlpha, Fred: 333-6565Beta, Fredd
20、ie: 656-0099Frederickson, Molly: 444-0981Gamma, Fred-George: 111-7676Zeta, Frederick: 431-0987The symbol “|“ is called “pipe.“ It pipes the output of the grep command into the input of the sort command.For more information on grep, consult% man grepheadUse this command to look at the head of a file.
21、 For example,% head essay.001displays the first 10 lines of the file essay.001 To see a specific number of lines, do this:% head -n 20 essay.001This displays the first 20 lines of the file.lsUse ls to see what files you have. Your files are kept in something called a directory.% lsfoo letter2foobar
22、letter3letter1 maple-assignment1%Note that you have six files. There are some useful variants of the ls command:% ls l*letter1 letter2 letter3%Note what happened: all the files whose name begins with “l“ are listed. The asterisk (*) is the “ wildcard“ character. It matches any string.lprThis is the
23、standard Unix command for printing a file. It stands for the ancient “line printer.“ See% man lprfor information on how it works. See print for information on our local intelligent print command.mkdirUse this command to create a directory.% mkdir essaysTo get “into“ this directory, do% cd essaysTo s
24、ee what files are in essays, do this:% lsThere shouldnt be any files there yet, since you just made it. To create files, see cat or emacs.moreMore is a command used to read text files. For example, we could do this:% more poemsThe effect of this to let you read the file “poems “. It probably will no
25、t fit in one screen, so you need to know how to “turn pages“. Here are the basic commands: q - quit more spacebar - read next page return key - read next line b - go back one pageFor still more information, use the command man more.mvUse this command to change the name of file and directories.% mv f
26、oo foobarThe file that was named foo is now named foobarncftpUse ncftp for anonymous ftp - that means you dont have to have a password.% ncftp Connected to get jokes.txtThe file jokes.txt is downloaded from the machine .printThis is a moderately intelligent print command.% print foo% print notes.ps
27、% print manuscript.dviIn each case print does the right thing, regardless of whether the file is a text file (like foo ), a postcript file (like notes.ps, or a dvi file (likemanuscript.dvi. In these examples the file is printed on the default printer. To see what this is, do% printand read the messa
28、ge displayed. To print on a specific printer, do this:% print foo jwb321% print notes.ps jwb321% print manuscript.dvi jwb321To change the default printer, do this:% setenv PRINTER jwb321pwdUse this command to find out what directory you are working in.% pwd/u/ma/jeremy% cd homework% pwd/u/ma/jeremy/
29、homework% lsassign-1 assign-2 assign-3% cd% pwd/u/ma/jeremy%Jeremy began by working in his “home“ directory. Then he cd d into his homework subdirectory. Cd means “ change directory“. He used pwd to check to make sure he was in the right place, then used ls to see if all his homework files were ther
30、e. (They were). Then he cdd back to his home directory.rmUse rm to remove files from your directory.% rm fooremove foo? y% rm letter*remove letter1? yremove letter2? yremove letter3? n%The first command removed a single file. The second command was intended to remove all files beginning with the str
31、ing “letter.“ However, our user (Jeremy?) decided not to remove letter3.rmdirUse this command to remove a directory. For example, to remove a directory called “essays“, do this:% rmdir essaysA directory must be empty before it can be removed. To empty a directory, use rm.rshUse this command if you w
32、ant to work on a computer different from the one you are currently working on. One reason to do this is that the remote machine might be faster. For example, the command% rsh solitudeconnects you to the machine solitude. This is one of our public workstations and is fairly fast.See also: telnetseten
33、v% echo $PRINTERlabprinter% setenv PRINTER myprinter% echo $PRINTERmyprintersortUse this commmand to sort a file. For example, suppose we have a file dict with contentsred rojogreen verdeblue azulwhite blancoblack negroThen we can do this:% sort dictblack negroblue azulgreen verdered rojowhite blanc
34、oHere the output of sort went to the screen. To store the output in file we do this:% sort dict dict.sorted You can check the contents of the file dict.sorted using cat , more , or emacs .tailUse this command to look at the tail of a file. For example,% tail essay.001displays the last 10 lines of th
35、e file essay.001 To see a specific number of lines, do this:% tail -n 20 essay.001This displays the last 20 lines of the file.tarUse create compressed archives of directories and files, and also to extract directories and files from an archive. Example:% tar -tvzf foo.tar.gzdisplays the file names i
36、n the compressed archive foo.tar.gz while% tar -xvzf foo.tar.gzextracts the files.telnetUse this command to log in to another machine from the machine you are currently working on. For example, to log in to the machine “solitude“, do this:% telnet solitudeSee also: rsh.wcUse this command to count th
37、e number of characters, words, and lines in a file. Suppose, for example, that we have a file dict with contentsred rojogreen verdeblue azulwhite blancoblack negroThen we can do this% wc dict5 10 56 tmpThis shows that dict has 5 lines, 10 words, and 56 characters.The word count command has several options, as illustrated below:% wc -l dict5 tmp% wc -w dict10 tmp% wc -c dict56 tmp
