Treebeard's Unix Cheat Sheet by Marc Kummel 17 March 1996 ----------------------------------------------------------------------------- This file is a text version of my Unix Cheat Sheet at . It will look best with a monospaced font like Courier at 80 characters per line. Email comments/corrections/cautions/additions to mkummel@rain.org. ----------------------------------------------------------------------------- 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 Unix 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 book _Unix Unbound_ by Harley Hahn (Osborne/McGraw Hill, 1994). ----------------------------------------------------------------------------- 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. (Doesn't work on RAIN?) apropos {keyword} Search for all Unix commands that match keyword, eg "apropos file". (Doesn't work 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} Good strategy: first list a group to rm {filespec} 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} < {fil1} 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 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} Do it on the server to reduce upload/ uuencode {filename} 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 listing ("ls -l") 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 alias q quota -v alias bye exit alias ls ls -F alias dir ls alias cdup cd .. alias motd more /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) 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 called hidden 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 them at your peril. Make backups first! Here's some of what I get when I type "ls -laF": .addressbook my email addressbook. .cshrc my C-shell startup info, important! .gopherrc my gopher setup. .history list of past commands. .login login init, important! .lynxrc my lynx setup for WWW. .ncftp/ hidden dir of ncftp stuff. .newsrc my list of subscribed newsgroups. .pinerc my pine setup for email. .plan text appears when I'm fingered, ok to edit. .profile Korn shell startup info, important! .project text appears when I'm fingered, ok to edit. .signature my signature file for mail and news, ok to edit. .tin/ hidden dir of my tin stuff for usenet. .ytalkrc my ytalk setup. ----------------------------------------------------------------------------- DOS and UNIX commands Action DOS UNIX ---------------------------------------------------------- change directory cd cd change file protection attrib chmod compare files comp diff copy file copy cp delete file del rm delete directory rd rmdir directory list dir ls edit a file edit pico environment set printenv find string in file find grep help help man make dir md mkdir move file move mv rename file ren mv show date and time date, time date show disk space chkdsk df show file type cat show file by screens type filename | more more sort data sort sort ----------------------------------------------------------------------------- Other Unix Links The Unix FAQ http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/faq/top.html UNIXhelp for users http://www.teleport.com/learn/unixhelp/TOP_.html #UNIX IRC homepage http://www.bsd.org/ The UNIX Reference Desk http://www.eecs.nwu.edu/unix.html ----------------------------------------------------------------------------- Copyright (c) 1996 by Marc Kummel mkummel@rain.org http://www.rain.org/~mkummel/