Posted by: lrrp | March 24, 2009

A Collection of Linux Commands

NOTICE this is ONLY the Basic list. I also offer a list of commands for:

TIP 1:
All of these commands should work from your command prompt (regardless which shell you’re using). Just in case some folks were not aware, you MUST press enter to invoke the command

TIP 2:
For this summary, please note that the EX: stands for example and is not part of the command. Commands are denoted in courier type font.

TIP 3:
If you need help understanding what the options are, or how to use a command, try adding this to the end of your command: –help

For example, for better understanding of the df command’s options, type:
df –help

Command Summary Use
Use cd to change directories Type cd followed by the name of a directory to access that directory.
Keep in mind that you are always in a directory and allowed access to any directories hierarchically above or below. Ex:
cd games

If the directory games is not located hierarchically below the current directory, then the complete path must be written out. Ex:
cd /usr/games

To move up one directory, use the shortcut command. Ex:
cd ..
Use clear to clear the command prompt Type clear to clean up your command prompt window.
This is especially helpful when you are typing lots of commands and need a clean window to help you focus.Ex:

This is also useful when you are getting ready to type a rather long command and do not wish to become confused by other details on the screen.
Use date to set your server’s date and time Type date followed by the two digit month, the two digit date, the two digit time, and two digit minutes. The syntax is easy enough and resembles this: MMDDhhmm
This command is helpful but must be used when superuser or logged in as root. Otherwise you will get an “Operation not permitted” reply.As root user you can use the command such as:
date 11081300

The above command will set the server date and time to the 11th month (November), the 8th day, at 1:00pm.
Use df to check disk space Typing df provides a very quick check of your file system disk space.
Type df -h to get a more easily readable version of the output. Notice that this command will include all applicable storage such as your hard disk/s (hda, hdb etc.) and your server SWAP file (shm). To list disk space including filesystem type:
df -h -T
Use finger to see who’s on the system Typing finger allows you to see who else is on the system or get detailed information about a person who has access to the system.
Type finger followed by the name of a user’s account to get information about that user. Or, type finger and press enter to see who’s on the system and what they are doing. Ex:
finger johndoe
Use logout to quit using the system Yep, you guessed it, typing logout will log your account out of the system.
Type logout at the prompt to disconnect from your Linux machine or to logout a particular user session from the system. Keep in mind that although rudimentary, leaving your critical account logged on may be a security concern. We always recommend promptly using logout when you are finished using your root account! Ex:
Use ls to list files and directories Type ls to see a list of the files and directories located in the current directory. If you’re in the directory named games and you type ls, a list will appear that contains files in the games directory and sub-directories in the games directory. Examples:
ls Mail
ls /usr/bin

Type ls -alt to see a list of all files (including .rc files) and all directories located in the current directory. The listing will include detailed, often useful information. Examples:
ls -alt
ls -alt /usr/bin
If the screen flies by and you miss seeing a number of files, try using the |more at the end like:
ls -alt |more* In Bash (Linux shell) often the abbreviated command L is available. To get a verbose listing of files and directories you could therefore simply type: l
Use man to pull up information about a Linux command Type man followed by a command to get detailed information about how to use the command. Ex:
man ls

Type man -k followed by a word to list all of the commands and descriptions that contain the word you specified. Ex:
man -k finger
Use more to read the contents of a file Type more followed by the name of a text file to read the file’s contents. Why do we exmphasize using this on a “text” file? Because most other types of files will look like garbage! Ex:
more testfile.txt
Use nano to start a text editor Typing nano will start a basic text editor on most Linux systems.
Type nano followed by the filename you wish to edit. This basic editor is quick and easy to use for beginners. However, it is very important that you also learn about other text editors available on Linux and UNIX systems. Click on this link to learn about others like emacs, vi, and pico. Ex:
nano /etc/security/access.conf
Use passwd to change your current password Type passwd and press enter. You’ll see the message Changing password for yourname.
At the Old password: prompt, type in your old password .
Then, at the Enter new password: prompt, type in your new password .
The system double checks your new password. Beside the Verify: prompt, type the new password and press again.

Create a secure password that combines parts of words and numbers. For instance, your dog’s name may be Rufus. He may have been born in 1980. Create a password that uses parts of both the name and date of birth, such as 80rufuS. Note the use of at least one capital letter. This is a fairly secure password and easy to remember.

Use pwd to list the name of your current directory Type pwd and hit enter. You’ll see the full name of the directory you are currently in. This is your directory path and is very handy. This is especially handy when you forget which directory you’ve changed to and are trying to run other commands.

Commands For Guru Wanna-bees
Now, this page is for people who are past newbie stage and ready for action!  For many more Linux commands and help, please look at our Linux Help page

We published this list to benefit ourselves by having one place to go to for those commands we use most often, and to give you a list of more advanced commands we know you will need! So here it is, a list of commands you’re going to need when running your Linux OS. Enjoy!

All of these commands should work from your command prompt (regardless which shell you’re using). And of course, if they don’t work or help you, we appologize way in advance!


Summary Use
du The du command prints a summary of the amount of information you have stored in your directories on the mounted disks.
syntax: du [options] path
ex: du -a /News

-s print the sum of bytes in your directories
-a print a line for each file in your directory

grep The grep command searches text files for a particular word or string of words. Very helpful when trying to find that needle in a haystack, like a particular line in a large log file.
syntax: grep textstring filename(s)
ex: grep century history.text.doc
Head Tail head: prints the beginning of a text file
tail: prints the end of a text file
These commands allow you to view parts of a text file.
tail -n 5 textfile.txt
head -n 5 textfile.txt

The examples above will print the last 5 lines of the file textfile.txt and then the first 5 lines.
locate Trying to find out where on your Linux server a particular file resides? Having a real nasty time doing it? If you have the Bash shell you can try using the locate command to identify where it is on your mounted drives.
Type: locate filename and press enter. Replace filename with the name of the file you are looking for. This is a real time saving command as you start navigating your Linux server!
If locate does not work for you try using which.
Nice Nohup Nice: runs programs/commands at a lower system priority
Nohup: runs nice programs even when you’re logged off the system
By using the two commands simultaneously, your large processes can continue to run, even when you have logged off the system and are relaxing.
Ex: nice nohup c program.c .
This command will allow the c compiler to compile program.c even when you have logged off the system.
psrelated to “stopped jobs” The ps command displays all of the existing processes. This command is also directly linked to issues with stopped processes (also known as “stopped jobs”).
Occasionally, you may see the message There are Stopped Jobs.
If you log off the system without properly stopping your jobs, some jobs/processes may remain in memory tying up the system and drawing unnecessary processing bandwidth.

Type ps and hit enter. This will list all of your current processes running, or stopped.

23036 pl S 0:00 -csh
23070 pl R 0:00 vi

The number under PID is the process identification number. To kill a process that is stopped, type: kill pid. Replace pid with the exact number of the process.
Ex: While in Vi, you accidentally press the wrong keys. Vi’s operation is stopped and you are kicked back to the prompt. To kill the stopped Vi command, you may type: kill 23070.

stty The stty command allows you to view a listing of your current terminal options. By using this command, you can also remap keyboard keys, tailoring to your needs.
Ex: stty and hit enter. This lists your terminal settings.
Ex: stty erase\^h . This remaps your erase key (backspace) to the Ctrl and h keys. From now on, holding down Ctrl and pressing h will cause a backspace. So you’re scratching your head asking why is this handy? You’ll see at some point how stty is also used for a number of other useful settings.
talk In order to contact someone who is on the system, at the prompt you type: talk accountname . Replace accountname with the full account name of the person. If you don’t want anyone to disturb you using the talk command, at the prompt
type: mesg n. This prevents others from using talk to reach you.
taralso related to gzip You’re bound to come across files that are g-zipped and tarred. Okay, now what? These are methods of compressing and storing directories and files in a single “file.” Most new Linux programs come off the web as something like coolnew-game.4-4-01.gz. This file is likely a tar file that has then been gzipped for compression. The way to handle these files is simple, but requires that you put the file into an appropriate directory. In other words, don’t plop the file in your root or /bin unless it belongs there.Now you can do a one fell swoop un-gzip it and untar it into its original form (usually multiple files in many sub directories) by typing: tar -xvzf *.gz

This will programmatically un-gzip and then untar all files in the current directory into their full original form including sub-directories etc. Please be careful where and how you run this!

w This command allows you to list all users’ and their processes who are currently logged in to the Linux server, or a particular user’s processes. Type: w to view all users’ processes. Type: w jsmith to view jsmith’s processes. We use this all the time from a system admin standpoint. Please also see more commands to get user information on this page. You need to know who logs on to your system! Okay, so you have a stand alone Linux box and no one else uses it? Try this command just to be sure. 😉
!! Don’t waste time and energy retyping commands at the prompt. Instead, use the ! option. To automatically re-display the last command you typed at the prompt, type: !! and press enter. Press again to invoke the command. You can also automatically re-display a command you typed earlier by using the ! and the first few letters of the command.
Ex: At the Linux prompt you had typed the command clear, followed by the command pico, followed by the command ftp. In order to re-display the clear command you type: !cl and press enter. In order to re-display the last command you typed, simply type: !! . Try it out. You’ll find this a time saver when dealing with long commands. Especially commands like tar!

(Really Linux)

Beginning Server Administrators – Updated

Every new Linux administrator wants a handy list of those essential commands needed for daily server management and maintenance. I’ve updated my beginner administrators command list in hopes that it will help you quickly become self sufficient in Linux server use.

Please feel free to share these commands. My only request is that you let others know where you got them so that I may be able to help them as well.

Please consider running these basic commands on occasion with the –help parameter to read through all of the options. For example try running the command: du –help

Also note that if a server command you run gives you an output that is far more than one single screen, you can use the option |more (referred to as pipe more). This will display the output one screen at a time. Press the space key for one page at a time, and the enter key for one line at a time. For example: ps -A |more

Beginner Server Administrator Commands


Summary Use

Command mostly used for checking existing Ethernet connectivity and IP address

Most common use: arp

This command should be used in conjunction with the ifconfig and route commands. It is mostly useful for me to check a network card and get the IP address quick. Obviously there are many more parameters, but I am trying to share the basics of server administration, not the whole book of commands.


Display filesystem information

Most common use: df -h

Great way to keep tabs on how much hard disk space you have on each mounted file system. You should also review our other commands like file permissions.


Display usage

Most common use, under a specific directory: du -a

Easily and quickly identify the size of files/programs in certain directories. A word of caution is that you should not run this command from the / directory. It will actually display size for every file on the entire Linux harddisk.


Find locations of files/directories quickly across entire filesystem

Most common use: find / -name appname -type d -xdev

(replace the word appname with the name of a file or application like gimp)This is a very powerful command and is best used when running as root or superuser. The danger is that you will potentially look across every single file on every filesystem, so the syntax is very important. The example shown allows you to search against all directories below / for the appname found in directories but only on the existing filesystem. It may sound complex but the example shown allows you to find a program you may need within seconds!

Other uses and more complex but beneficial functions include using the -exec or execute a command.
You may also try the commands: locate or try slocate


Command line tool to configure or check all network cards/interfaces

Most common uses: ifconfig and also ifconfig eth0

Using the plain ifconfig command will show you the details of all the already configured network cards or interfaces. This is a great way to get a check that your network hardware is working properly. You may also benefit from this review of server configuration. Using the many other options of ifconfig such as the one listed allows you to assign a particular interface a static IP address. I only show an example and not a real world command above. Also review some commands for file permissions here.. Your best bet, if you want to configure your network card using this command is to first read the manual pages. You access them by typing: man ifconfig


Allows you to change the server bootup on a specific runlevel

Most common use: init 5

This is a useful command, when for instance a servers fails to identify video type, and ends up dropping to the non-graphical boot-up mode (also called runlevel 3).

The server runlevels rely on scripts to basically start up a server with specific processes and tools upon bootup. Runlevel 5 is the default graphical runlevel for Linux servers. But sometimes you get stuck in a different mode and need to force a level. For those rare cases, the init command is a simple way to force the mode without having to edit the inittab file.

Of course, this command does not fix the underlying problem, it just provides a fast way to change levels as needed. For a more permanent correction to the runlevel, edit your /etc/inittab file to state: id:5:initdefault:

joe or nano

Easy to use command line editors that are often included with the major Linux flavors

Most common uses:
joe filename
nano filename

A real world example for you to get a better sense on how this works:
nano /etc/dhcp3/dhcpd.conf
This allows you to edit using nano the dhcpd.conf configuration file from the command line.

Maybe you are not up to speed on vi, or never learned how to use emacs? On most Linux flavors the text editor named joe or one named nano are available. These basic but easy to use editors are useful for those who need a text editor on the command line but don’t know vi or emacs. Although, I do highly recommend that you learn and use Vi and Emacs editors as well. Regardless, you will need to use a command line editor from time to time. You can also use cat and more commands to list contents of files, but this is basic stuff found under the basic linux commands listing. Try: more filename to list contents of the filename.


Summary of network connections and status of sockets

Most common uses: netstat and also netstat |head and also netstat -r

Netstat command simply displays all sockets and server connections. The top few lines are usually most helpful regarding webserver administration. Therefore if you are doing basic webserver work, you can quickly read the top lines of the netstat output by including the |head (pipe and head commands). Using the –r option gives you a very good look at the network routing addresses. This is directly linked to the route command.


Checks the domain name and IP information of a server

Most common use: nslookup

You are bound to need this command for one reason or another. When performing server installation and configuration this command gives you the existing root server IP and DNS information and can also provide details from other remote servers. Therefore, it is also a very useful security command where you can lookup DNS information regarding a particular host IP that you may see showing up on your server access logs. Note there are some other commands like file permissions that may also help. There is a lot more to this command and using the man pages will get you the details by typing: man nslookup


Sends test packets to a specified server to check if it is responding properly

Most common use: ping (replace the with a true IP address)

This is an extremely useful command that is necessary to test network connectivity and response of servers. It creates a series of test packets of data that are then bounced to the server and back giving an indication whether the server is operating properly.

It is the first line of testing if a network failure occurs. If ping works but for instance FTP does not, then chances are that the server is configured correctly, but the FTP daemon or service is not. However, if even ping does not work there is a more significant server connectivity issue… like maybe the wires are not connected or the server is turned off! The outcome of this command is pretty much one of two things. Either it works, or you get the message destination host unreachable. It is a very fast way to check even remote servers.


Lists all existing processes on the server

Most common uses: ps and also ps -A |more

The simple command will list every process associated with the specific user running on the server. This is helpful in case you run into problems and need to for instance kill a particular process that is stuck in memory. On the other hand, as a system administrator, I tend to use the -A with the |more option. This will list every process running on the server one screen at a time. Read more of our commands on our help page. I use ps to quickly check what others are goofing with on my servers and often find that I’m the one doing the dangerous goofing!


Removes/deletes directories and files

Most common use: rm -r name (replace name with your file or directory name)

The –r option forces the command to also apply to each subdirectory within the directory. For instance if you are trying to delete the entire contents of the directory x which includes directories y and z this command will do it in one quick process. That is much more useful than trying to use the rmdir command after deleting files! Instead use the rm -r command and you will save time and effort. You may already have known this but since server administrators end up spending a lot of time making and deleting I included this tip!


Lists the routing tables for your server

Most common use: route -v

This is pretty much the exact same output as the command netstat -r. You can suit yourself which you prefer to run. I tend to type netstat commands a lot more than just route and so it applies less to my situation, but who knows, maybe you are going to love and use route the most!


Deletes a file securely by overwriting its contents

Most common use: shred -v filename (replace filename with your specific file)

The -v option is useful since it provides extra view of what exactly the shred tool is doing while you wait. On especially BIG files this could take a bit of time. The result is that your file is so thoroughly deleted it is very unlikely to ever be retrieved again. This is especially useful when trying to zap important server related files that may include confidential information like user names or hidden processes. It is also useful for deleting those hundreds of love notes you get from some of the users on your server, another bonus of being a server administrator. 🙂


The super-user do command that allows you to run specific commands that require root access.

Most common use: sudo command (replace command with your specific one)

This command is useful when you are logged into a server and attempt a command that requires super-user or root privileges. In most cases, you can simply run the command through sudo, without having to log in as root. In fact, this is a very beneficial way to administer your server without daily use of the root login, which is potentially dangerous.

Note there are other commands for file permissions here. Below is a simple example of the sudo capabilities:
sudo cd /root
This command allows you to change directories to the /root without having to login as root. Note that you must enter the root password once, when running a sudo command.


Displays many system statistics and details regarding active processes

Most common use: top

This is a very useful system administrator tool that basically gives you a summary view of the system including number of users, memory usage, CPU usage, and active processes. Often during the course of a day when running multiple servers, one of my Xwindows workstations just displays the top command from each of the servers as a very quick check of their status and stability.


Allows you to change the timestamp on a file.

Most common use: touch filename

Using the basic touch command, as above, will simply force the current date and time upon the specified file. This is helpful, but not often used.

However, another option that I’ve used in the past when administering servers, is to force a specific timestamp on a set of files in a directory. Read more of our commands on our help page.

For instance, to force a specific date and time upon all files in a directory, type:
touch *

You can also force a specific date/time stamp using the -t option like this: touch -t200103041200.00 *
The command above will change all files in the current directory to take on the new date of March 4th, 2001 at noon. The syntax follows this pattern:

YYYY represents the four digit year, then the two digit month, day, hour and minutes. You can even specify seconds as noted above. In any case, this is a useful way to control timestamps on any files on your server.


Traces the existing network routing for a remote or local server

Most common use: traceroute hostname

(replace hostname with the name of your server such as

This is a very powerful network command that basically gives the exact route between your machine and a server. In some cases you can actually watch the network hops from country to country across an ocean, through data centers, etc. Read more of our commands on our help page.

This comes in handy when trying to fix a network problem, such as when someone on the network can not get access to your server while others can. This can help identify the break or error along the network line. One strong note to you is not to misuse this command! When you run the traceroute everyone of those systems you see listed also sees YOU doing the traceroute and therefore as a matter of etiquette and respect this command should be used when necessary not for entertainment purposes. A key characteristic of gainfully employed server administrators: knowing when to use commands and when not to use them!


An extension of the who command that displays details of all users currently on the server

Most common uses: w

This is a very important system admin tool I use commonly to track who is on the server and what processes they are running. It is obviously most useful when run as a superuser.

The default setting for the w command is to show the long list of process details. You can also run the command w -s to review a shorter process listing, which is helpful when you have a lot of users on the server doing a lot of things! Remember that this is different than the who command that can only display users not their processes.


Tool used to monitor who is on the system and many other server related characteristics

Most common uses: who and also who -q and also who -b

The plain command just lists the names of users currently on the server. Using the -q option allows you to quickly view just the total number of users on the system. Using the -b option reminds you how long it has been since you rebooted that stable Linux server! One of my servers had a -b of almost three years! Yes, that’s why we at call it really Linux!

Please realize that these are just a few select commands for getting started in the world of Linux Server Administration.

Manipulating Directories and Files

If you’re a beginner, it may help you to type the command
ls -alt to list all of your current files and directories. Type ls -alt after you try each command below to be certain it worked properly.

All of these commands should work from your command prompt (regardless which shell you’re using). And of course, if they don’t work or help you, we appologize.

Directory Related Commands


Summary Use
cd Use cd to change directories. Type cd followed by the name of a directory to access that directory. Keep in mind that you are always in a directory and can navigate to directories hierarchically above or below. Ex:
cd games
If the directory games is not located hierarchically below the current directory, then the complete path must be
written out. Ex:
cd /usr/games
To move up one directory, use the shortcut command. Ex:
cd ..
Use cp -r to copy a directory and all of its contents
Type cp -r followed by the name of an existing directory and the name of the new directory. Ex:
cp -r testing newdir
You must include the -r or you’ll see the following message:
cp: testing is a directory and -r not specified.
This command saves you time if you need to make a mirror image of a directory packed with files.
mkdir Use mkdir to make/create a brand new directory
Type mkdir followed by the name of a directory. Ex:
mkdir testdir

mv Use mv to change the name of a directory
Type mv followed by the current name of a directory and the new name of the directory. Ex:
mv testdir newnamedir

pwd Trying to find out where on your Linux server you currently are located? The pwd (print working directory) command will show you the full path to the directory you are currently in. This is very handy to use, especially when performing some of the other commands on this page!

Use rmdir to remove an existing directory (assuming you have permissions set to allow this).
Type rmdir followed by a directory’s name to remove it. Ex:
rmdir testdir

You CAN’T remove a directory that contains files with this command. A more useful command is rm -r that removes directories and files within the directories. You can read more about this in Commands for Beginning Admins

The rmdir command is used mostly to remove empty directories. If you have a desire to use this command then you’ll need to delete or move the files before attempting to remove a full directory. For more help please read the mv command and also

File Related Commands.

Manipulating Files

Included in this section are the commands needed to copy, delete, move, and rename files. Security and permissions are also reviewed below in the chmod command.

A beginner? Then it may help you to type the command ls -alt to list all of your current files and directories before you start, so you can see your directory and files listed.

All of these commands should work from your command prompt (regardless which shell you’re using). And of course, if they don’t work or help you, I apologize.

Manipulating Files


Summary Use
chmod The chmod command allows you to alter access rights to files and directories. All files and directories have security permissions that grant the user particular groups’ or all other users’ access.

To view your files’ settings, at the shell prompt type: ls -alt

You should see some files with the following in front of them (an example follows):

total 4
drwxrwsr-x 7 reallyli reallyli 1024 Apr 6 14:30 .
drwxr-s–x 22 reallyli reallyli 1024 Mar 30 18:20 ..
d-wx-wx-wx 3 reallyli reallyli 1024 Apr 6 14:30 content
drwxr-xr-x 2 reallyli reallyli 1024 Mar 25 20:43 files

What do the letters mean in front of the files/directories mean?
r indicates that it is readable (someone can view the file’s contents)
w indicates that it is writable (someone can edit the file’s contents)
x indicates that it is executable (someone can run the file, if executable)
indicates that no permission to manipulate has been assigned

When listing your files, the first character lets you know whether you’re looking at a file or a directory. It’s not part of the security settings. The next three characters indicate Your access restrictions. The next three indicate your group‘s permissions, and finally other users’ permissions.

Use chmod followed by the permission you are changing. In very simple form this would be:
chmod 755 filename
The example above will grant you full rights, group rights to execute and read, and all others access to execute the file.

# Permission
7 full
6 read and write
5 read and execute
4 read only
3 write and execute
2 write only
1 execute only
0 none

Still confused? Use the table above to define the settings for the three “users.” In the command, the first number refers to your permissions, the second refers to group, and the third refers to general users.

Typing the command: chmod 751 filename

gives you full access, the group read and execute, and all others execute only permission.

cp Type cp followed by the name of an existing file and the name of the new file.

cp newfile newerfile
To copy a file to a different directory (without changing th
e file’s name), specify the directory instead of the new
filename. Ex:
cp newfile testdir
To copy a file to a different directory and create a new file name, you need to specify a directory/a new file name. Ex:
cp newfile testdir/newerfile
cp newfile ../newerfile
The .. represents one directory up in the hierarchy.

file Type file followed by the name of an existing file in the directory.

file emergency3_demo.exe

OUTPUT: MS-DOS executable (EXE)

This command allows you to figure out what the file type is and how to use it. For instance the command will tell you whether it is an executable, a compressed file and which type, or something unusual.

This command is simplistic, but often can allow you to determine why a file does not respond the way you expect.

mv Type mv followed by the current name of a file and the new name of the file.

mv oldfile newfile

Type mv followed by the name of a file and the new directory where you’d like to place the file. Ex:
mv newfile testdir
This moves the file named newfile to an existing directory named testdir. Be certain you’re specifying a directory
name or the mv command alters the name of the file instead of moving it.

rm Type rm followed by the name of a file to remove the file.

rm newfile
Use the wildcard character to remove several files at once. Ex:
rm n*
This command removes all files beginning with n.
Type rm -i followed by a filename if you’d like to be prompted before the file is actually removed. Ex:
rm -i newfile
rm -i n*
By using this option, you have a chance to verify the removal of each file. The -i option is very handy when removing
a number of files using the wildcard character *.

(Really Linux)



  1. […] lrrp added an interesting post today on A Collection of Linux Commands « Java DevZoneHere’s a small readingMost common use: ping (replace the with a true IP address). This is an extremely useful command that is necessary to test network connectivity and response of servers. It creates a series of test packets of data that … […]

  2. cheers…

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