The Most Important UNIX Commands
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TOP 50 IMPORTANT UNIX COMMANDS
| Command with Common Usage | Description |
|---|---|
| alias [ name [ string ] ] | Make name an alias for string |
| awk script [ file ] | See description below |
| basename [ path ] | Return everything after last / in path |
| bg [ %job-id ] | Put job in the background |
| break | Escape from control loop |
| cat [ file ... ] | Concatenate and display files |
| cd [ dir ] | Change working directory |
| chmod mode file | Change permissions mode of file |
| continue | Continue next iteration of control loop |
| cp source target | Copy source file to target file |
| diff file1 file2 | Display differences between file1 and file2 |
| dirname [ path ] | Return everything before last / in path |
| echo [ -n ] string | Write string to standard output |
| exit [ value ] | Exit from current shell with optional return value |
| fg [ %job-id ] | Return job to foreground |
| foreach word ( list ) [ ... ] end | Succesively set word to elements in list |
| grep [ -i ] pattern [ file ] | Search for pattern in file |
| head [ -number ] [ file ] | Print first few lines of file |
| hostname | Print name of current host |
| if ( expr ) [ then ... else ... endif ] | Conditional evaluation (else if also supported) |
| kill [ -signal ] pid | Terminate or signal a process |
| ln -s source [ target ] | Make “symbolic” link from target to source |
| ls [ -alrt ] | List contents of directory |
| make | Maintain and regenerate related programs and files |
| man [ -k ] command | Display man page for a command or keyword |
| mkdir dir | Make directory |
| more [ file ... ] | Browse or page through a text file |
| mv source target | Move or rename source to target |
| nice [ -priority ] command | Execute command with specific priority |
| ps | Print information about active processes |
| pwd | Return working directory name |
| rehash | Refresh command search path |
| renice priority pid | Change process priority |
| rm file | Remove file |
| rmdir dir | Remove directory |
| sed script [ file ] | See description below |
| set [ variable [ = value ] ] | Set shell variable to value (opposite unset) |
| setenv [ VARIABLE [ word ] ] | Set environment variable to word (opposite unsetenv) |
| sort [ file ] | Sort lines of text file |
| source file | Execute commands from text file |
| switch ( expr ) case: [ ... ] endsw | Choose from among a list of actions (like in C) |
| tail [ -number ] [ file ] | Print last few lines of file |
| tee [ file ] | Replicate standard output |
| time command | Time a command |
| top | Display information about top CPU processes |
| touch file | Create empty file or update access & mod times |
| uptime | Show system load and how long system has been up |
| w | Display information about logged-in users |
| wc [ file ... ] | Count lines, characters, and bytes in file |
| whatis command | Display summary about a command |
| which command (also where command) | Locate a command; display its pathname or alias |
| while ( expr ) [ ... ] end | Loop while expr true |
Deep dive to widely used unix Command Advance
Basic File Commands:
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| |
| more filename Displays a file on the screen and pauses |
| at the end of each screenful. "Spacebare"|
| scrolls down one page, RETURN one line |
| at a time options. |
| pg filename Displays a file on the screen and pauses |
| at the end of each screenful. RETURN |
| scrolls down one page |
| |
| cat filename Displays a file on the screen without |
| pausing at the end of the screen. Use |
| <CTRL><S> to stop screen output and |
| <CTRL><Q> to restart output. There will |
| be a time delay before screen output can |
| be stopped. |
| |
| cp filename newfilename Make a second copy of a file. |
| |
| mv filename newfilename Renames (moves) a file to a new filename.|
| |
| rm filename(s) Deletes (removes) one or more files. |
| |
| rmdir directoryname Deletes (removes) an empty directory. |
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Note: On standard UNIX systems there is no built in undelete
command. If a file is deleted with rm it is gone forever
unless there is a copy of the file on tape backup.
Basic Directory Commands:
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| |
| pwd Shows your current connected directory. |
| |
| cd directory Changes your current connected directory. |
| |
| ls Gives a directory listing. |
| |
| ls -l Gives a long form directory listing including |
| protections and file sizes. See the manual page for ls |
| by typing man ls if you are interested in other options |
| to the ls command. |
| |
| chmod filename Changes permissions to read, write or execute a file |
| e.g.: "chmod 777 *" gives read, write and execute |
| permission to everyone and to all files in the directory|
| *="joker", for more information see |
| http://www.sp.uconn.edu/workshops/unix.shell.basics.workshop.html |
| |
| ls -a Gives a directory list of all files in the directory, |
| including files which start with a ".". These are |
| typically parameter files and are normally invisible. |
| |
| du Shows the disk usage of the current directory. |
| |
| mkdir Makes a new directory |
| |
| rmdir Removes an existing empty directory. |
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One should also be aware of the use of the following UNIX directory
abbreviations:
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| . Current working directory |
| |
| .. Parent directory of current working directory |
| |
| $HOME User's home directory |
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Commands for Aborting Programs:
Usually it is best to leave programs using the quit or exit commands, however
occasionally it is necessary to terminate a running program. Here are some
useful commands for doing this:
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| |
| <CTRL><C> Aborts a running program without the option of restarting |
| it later. |
| |
| <CTRL><Z> Pauses a program and returns the user to the genes% |
| prompt. The program can be restarted by typing fg |
| (foreground). If you type bg (background) the job will |
| also be started again, but in background mode. |
| |
| kill psid Kills a process with the given process ID. This number is |
| obtained using the ps command. |
| |
| <CTRL><D> Terminates a UNIX shell such as csh or sh. Use logout to |
| exit from your top level login shell. This command only |
| work at the genes% prompt. |
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Here are some commands which give information about your login
sessions and jobs which you are running:
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| |
| uptime Prints the current time, the length of time the computer has |
| been running since the last shutdown, the average number of |
| users on the system, and the average system loads over 1, 5, |
| and 15 minutes. |
| |
| ps Shows your current processes and their status (running, |
| sleeping, idle, terminated, etc.). |
| |
| jobs Shows your active jobs and their status (running or stopped).|
| |
| top Shows the most active processes on the entire machine and the|
| portion of CPU cycles assigned to running processes. Press |
| "q" to quit from top. |
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UNIX Command Summary:
Here is a reference list of some common UNIX commands.
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|_Command_________Function________________________________________________|
| |
| <CTRL><C> Aborts a command or program. |
| <CTRL><D> Terminates a UNIX shell level; closes a file. |
| <CTRL><> Toggles terminal scrolling. |
| <CTRL><S> Stops terminal scrolling. |
| <CTRL><Q> Continues terminal scrolling. |
| <CTRL><Z> Suspends running job. |
|_________________________________________________________________________|
| |
| at Submit script to the at queue for execution later. |
| atq Lists jobs waiting in batch queue |
| atrm Removes a job from the at queue. |
| bg Resumes a suspended job in background mode. |
| cat Shows file on screen. Can also be used to concatenate |
| file. |
| chmod Sets file or directory protections. |
| chsh Changes login shell declaration. |
| cp Copies files. |
| du Shows disk usage of a directory and its files. |
| emacs Enters the emacs full screen text editor. |
| fg Brings a background job back into interactive mode. |
| finger username Identifies a user. |
| groups List the privilege groups to which a user belongs. |
| jobs Shows active jobs and their status. |
| kill Kills a running process. |
| logout Ends your terminal session with ICGEBnet. |
| ls Shows listing of files belonging to a directory. |
| ls -a Shows listing of files including hidden files. |
| ls -l Shows verbose listing of files including protections, |
| size, date created, and originator. |
| man command Shows the on-line manual page for a UNIX command. |
| more Shows a file stopping at the end of each page. Can also|
| move backwards or search for a specific pattern. |
| mv Renames (moves) a file. |
| passwd Changes account password. |
| ps Shows your processes and their status. |
| quota Shows disk usage and permanent and working disk quotas. |
| rm Removes (deletes) files. |
| script Records terminal output to a file. |
| stty Sets various terminal parameters. |
| talk Interactively converse with another logged-in user. |
| top Shows the most active processes on the system. |
| umask Sets the file creation mask for file protections. |
| w Lists current logged-in users. |
| who Lists current logged-in users. |
| whoami Lists your username. |
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The ancestor of this file was obtained from genes.icgeb.trieste.it