Linux Bash Shell Cheat Sheet for Beginners

Linux Bash Shell Cheat Sheet for Beginners

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  freeworld.posterous.com Linux Bash Shell Cheat Sheet (works with about every distribution, except for apt-get which is Ubuntu/Debian exclusive) Legend: Everything in “<>” is to be replaced, ex: <fileName> --> iLovePeanuts.txt Don't include the '=' in your commands '..' means that more than one file can be affected with only one command ex: rm file.txt file2.txt movie.mov .. ..
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  Linux Bash ShellCheat Sheet Basic Commands Basic Terminal Shortcuts Basic file manipulation CTRL L = Clear the terminal cat <fileName> = show content of file CTRL D = Logout (less, more) SHIFT Page Up/Down = Go up/down the terminal head = from the top CTRL A = Cursor to start of line -n <#oflines> <fileName> CTRL E = Cursor the end of line CTRL U = Delete left of the cursor tail = from the bottom CTRL K = Delete right of the cursor -n <#oflines> <fileName> CTRL W = Delete word on the left CTRL Y = Paste (after CTRL U,K or W) mkdir = create new folder TAB = auto completion of file or command mkdir myStuff .. CTRL R = reverse search history mkdir myStuff/pictures/ .. !! = repeat last command CTRL Z = stops the current command (resume with fg in foreground or bg in background) cp image.jpg newimage.jpg = copy and rename a file Basic Terminal Navigation cp image.jpg <folderName>/ = copy to folder cp image.jpg folder/sameImageNewName.jpg ls -a = list all files and folders cp -R stuff otherStuff = copy and rename a folder ls <folderName> = list files in folder cp *.txt stuff/ = copy all of *<file type> to folder ls -lh = Detailed list, Human readable ls -l *.jpg = list jpeg files only mv file.txt Documents/ = move file to a folder ls -lh <fileName> = Result for file only mv <folderName> <folderName2> = move folder in folder mv filename.txt filename2.txt = rename file cd <folderName> = change directory mv <fileName> stuff/newfileName if folder name has spaces use “ “ mv <folderName>/ .. = move folder up in hierarchy cd / = go to root cd .. = go up one folder, tip: ../../../ rm <fileName> .. = delete file (s) rm -i <fileName> .. = ask for confirmation each file du -h: Disk usage of folders, human readable rm -f <fileName> = force deletion of a file du -ah: “ “ “ files & folders, Human readable rm -r <foldername>/ = delete folder du -sh: only show disc usage of folders touch <fileName> = create or update a file pwd = print working directory ln file1 file2 = physical link man <command> = shows manual (RTFM) ln -s file1 file2 = symbolic link
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  Linux Bash ShellCheat Sheet Basic Commands Researching Files Extract, sort and filter data The slow method (sometimes very slow): grep <someText> <fileName> = search for text in file -i = Doesn't consider uppercase words locate <text> = search the content of all the files -I = exclude binary files locate <fileName> = search for a file grep -r <text> <folderName>/ = search for file names sudo updatedb = update database of files with occurrence of the text find = the best file search tool (fast) With regular expressions: find -name “<fileName>” find -name “text” = search for files who start with the word text grep -E ^<text> <fileName> = search start of lines find -name “*text” = “ “ “ “ end “ “ “ “ with the word text grep -E <0-4> <fileName> =shows lines containing numbers 0-4 Advanced Search: grep -E <a-zA-Z> <fileName> = retrieve all lines with alphabetical letters Search from file Size (in ~) find ~ -size +10M = search files bigger than.. (M,K,G) sort = sort the content of files sort <fileName> = sort alphabetically Search from last access sort -o <file> <outputFile> = write result to a file find -name “<filetype>” -atime -5 sort -r <fileName> = sort in reverse ('-' = less than, '+' = more than and nothing = exactly) sort -R <fileName> = sort randomly sort -n <fileName> = sort numbers Search only files or directory’s find -type d --> ex: find /var/log -name "syslog" -type d wc = word count find -type f = files wc <fileName> = nbr of line, nbr of words, byte size -l (lines), -w (words), -c (byte size), -m More info: man find, man locate (number of characters) cut = cut a part of a file -c --> ex: cut -c 2-5 names.txt (cut the characters 2 to 5 of each line) -d (delimiter) (-d & -f good for .csv files) -f (# of field to cut) more info: man cut, man sort, man grep
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  Linux Bash ShellCheat Sheet Basic Commands Time settings (continued) date = view & modify time (on your computer) crontab = execute a command regularly -e = modify the crontab View: -l = view current crontab date “+%H” --> If it's 9 am, then it will show 09 -r = delete you crontab date “+%H:%M:%Ss” = (hours, minutes, seconds) In crontab the syntax is %Y = years <Minutes> <Hours> <Day of month> <Day of week (0-6, Modify: 0 = Sunday)> <COMMAND> MMDDhhmmYYYY Month | Day | Hours | Minutes | Year ex, create the file movies.txt every day at 15:47: 47 15 * * * touch /home/bob/movies.txt sudo date 031423421997 = March 14 th 1997, 23:42 * * * * * --> every minute at 5:30 in the morning, from the 1st to 15th each month: Execute programs at another time 30 5 1-15 * * at midnight on Mondays, Wednesdays and Thursdays: use 'at' to execute programs in the future 0 0 * * 1,3,4 every two hours: Step 1, write in the terminal: at <timeOfExecution> ENTER 0 */2 * * * ex --> at 16:45 or at 13:43 7/23/11 (to be more precise) every 10 minutes Monday to Friday: or after a certain delay: */10 * * * 1-5 at now +5 minutes (hours, days, weeks, months, years) Step 2: <ENTER COMMAND> ENTER Execute programs in the background repeat step 2 as many times you need Step 3: CTRL D to close input Add a '&' at the end of a command ex --> cp bigMovieFile.mp4 & atq = show a list of jobs waiting to be executed nohup: ignores the HUP signal when closing the console atrm = delete a job n°<x> (process will still run if the terminal is closed) ex (delete job #42) --> atrm 42 ex --> nohup cp bigMovieFile.mp4 sleep = pause between commands jobs = know what is running in the background with ';' you can chain commands, ex: touch file; rm file you can make a pause between commands (minutes, hours, days) fg = put a background process to foreground ex --> touch file; sleep 10; rm file <-- 10 seconds ex: fg (process 1), f%2 (process 2) f%3, ...
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  Linux Bash ShellCheat Sheet Basic Commands Process Management Create and modify user accounts w = who is logged on and what they are doing sudo adduser bob = root creates new user sudo passwd <AccountName> = change a user's password tload = graphic representation of system load average sudo deluser <AccountName> = delete an account (quit with CTRL C) addgroup friends = create a new user group ps = Static process list delgroup friends = delete a user group -ef --> ex: ps -ef | less -ejH --> show process hierarchy usermod -g friends <Account> = add user to a group -u --> process's from current user usermod -g bob boby = change account name usermod -aG friends bob = add groups to a user with- top = Dynamic process list out loosing the ones he's already in While in top: • q to close top File Permissions • h to show the help • k to kill a process chown = change the owner of a file ex --> chown bob hello.txt CTRL C to top a current terminal process chown user:bob report.txt = changes the user owning report.txt to 'user' and the group owning it to 'bob' kill = kill a process -R = recursively affect all the sub folders You need the PID # of the process ex --> chown -R bob:bob /home/Daniel ps -u <AccountName> | grep <Application> Then chmod = modify user access/permission – simple way kill <PID> .. .. .. u = user kill -9 <PID> = violent kill g = group o = other killall = kill multiple process's ex --> killall locate d = directory (if element is a directory) l = link (if element is a file link) extras: r = read (read permissions) sudo halt <-- to close computer w = write (write permissions) sudo reboot <-- to reboot x = eXecute (only useful for scripts and programs)
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  Linux Bash ShellCheat Sheet Basic Commands File Permissions (continued) Flow Redirection (continued) '+' means add a right terminal output: '-' means delete a right Alex '=' means affect a right Cinema Code ex --> chmod g+w someFile.txt Game (add to current group the right to modify someFile.txt) Ubuntu more info: man chmod Another example --> wc -m << END Flow redirection Chain commands Redirect results of commands: '|' at the end of a command to enter another one ex --> du | sort -nr | less '>' at the end of a command to redirect the result to a file ex --> ps -ejH > process.txt Archive and compress data '>>' to redirect the result to the end of a file Archive and compress data the long way: Redirect errors: Step 1, put all the files you want to compress in '2>' at the end of the command to redirect the result to a file the same folder: ex --> mv *.txt folder/ ex --> cut -d , -f 1 file.csv > file 2> errors.log '2>&1' to redirect the errors the same way as the standard output Step 2, Create the tar file: tar -cvf my_archive.tar folder/ Read progressively from the keyboard -c : creates a .tar archive -v : tells you what is happening (verbose) <Command> << <wordToTerminateInput> -f : assembles the archive into one file ex --> sort << END <-- This can be anything you want > Hello Step 3.1, create gzip file (most current): > Alex gzip my_archive.tar > Cinema to decompress: gunzip my_archive.tar.gz > Game > Code Step 3.2, or create a bzip2 file (more powerful but slow): > Ubuntu bzip2 my_archive.tar > END to decompress: bunzip2 my_archive.tar.bz2
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  Linux Bash ShellCheat Sheet Basic Commands Archive and compress data (continued) Installing software step 4, to decompress the .tar file: When software is available in the repositories: tar -xvf archive.tar archive.tar sudo apt-get install <nameOfSoftware> ex--> sudo apt-get install aptitude Archive and compress data the fast way: If you download it from the Internets in .gz format gzip: tar -zcvf my_archive.tar.gz folder/ (or bz2) - “Compiling from source” decompress: tar -zcvf my_archive.tar.gz Documents/ Step 1, create a folder to place the file: mkdir /home/username/src <-- then cd to it bzip2: tar -jcvf my_archive.tar.gz folder/ decompress: tar -jxvf archive.tar.bz2 Documents/ Step 2, with 'ls' verify that the file is there (if not, mv ../file.tar.gz /home/username/src/) Show the content of .tar, .gz or .bz2 without decompressing it: Step 3, decompress the file (if .zip: unzip <file>) gzip: <-- gzip -ztf archive.tar.gz Step 4, use 'ls', you should see a new directory bzip2: Step 5, cd to the new directory bzip2 -jtf archive.tar.bz2 Step 6.1, use ls to verify you have an INSTALL file, tar: then: more INSTALL tar -tf archive.tar If you don't have an INSTALL file: Step 6.2, execute ./configure <-- creates a makefile tar extra: Step 6.2.1, run make <-- builds application binaries tar -rvf archive.tar file.txt = add a file to the .tar Step 6.2.2 : switch to root --> su Step 6.2.3 : make install <-- installs the software You can also directly compress a single file and view the file Step 7, read the readme file without decompressing: Step 1, use gzip or bzip2 to compress the file: gzip numbers.txt Step 2, view the file without decompressing it: zcat = view the entire file in the console (same as cat) zmore = view one screen at a time the content of the file (same as more) zless = view one line of the file at a time (same as less)