25 Best Linux Commands

As a Linux user you’ll come to learn and love certain commands. Remembering these commands is the toughest part.

Some people use cheat-sheets, some create scripts, and some just refer to website for their fix. Here I have posted the 25 top command line snippets. Please remember to always read man pages for any command before running any commands or applications

25) sshfs name@server:/path/to/folder /path/to/mount/point
Mount folder/filesystem through SSH
Install SSHFS from http://fuse.sourceforge.net/sshfs.html
Will allow you to mount a folder security over a network.

24) !!:gs/foo/bar
Runs previous command replacing foo by bar every time that foo appears
Very useful for rerunning a long command changing some arguments globally.
As opposed to ^foo^bar, which only replaces the first occurrence of foo, this one changes every occurrence.

23) mount | column -t
currently mounted filesystems in nice layout
Particularly useful if you’re mounting different drives, using the following command will allow you to see all the filesystems currently mounted on your computer and their respective specs with the added benefit of nice formatting.

22) <space>command
Execute a command without saving it in the history
Prepending one or more spaces to your command won’t be saved in history.
Useful for pr0n or passwords on the commandline.

21) ssh user@host cat /path/to/remotefile | diff /path/to/localfile –
Compare a remote file with a local file
Useful for checking if there are differences between local and remote files.

20) mount -t tmpfs tmpfs /mnt -o size=1024m
Mount a temporary ram partition
Makes a partition in ram which is useful if you need a temporary working space as read/write access is fast.
Be aware that anything saved in this partition will be gone after your computer is turned off.

19) dig +short txt <keyword>.wp.dg.cx
Query Wikipedia via console over DNS
Query Wikipedia by issuing a DNS query for a TXT record. The TXT record will also include a short URL to the complete corresponding Wikipedia entry.

18) netstat -tlnp
Lists all listening ports together with the PID of the associated process
The PID will only be printed if you’re holding a root equivalent ID.

17) dd if=/dev/dsp | ssh -c arcfour -C username@host dd of=/dev/dsp
output your microphone to a remote computer’s speaker
This will output the sound from your microphone port to the ssh target computer’s speaker port. The sound quality is very bad, so you will hear a lot of hissing.

16) echo “ls -l” | at midnight
Execute a command at a given time
This is an alternative to cron which allows a one-off task to be scheduled for a certain time.



15) curl -u user:pass -d status=”Tweeting from the shell” http://twitter.com/statuses/update.xml
Update twitter via curl

14) ssh -N -L2001:localhost:80 somemachine
start a tunnel from some machine’s port 80 to your local post 2001
now you can acces the website by going to http://localhost:2001/

13) reset
Salvage a borked terminal
If you bork your terminal by sending binary data to STDOUT or similar, you can get your terminal back using this command rather than killing and restarting the session. Note that you often won’t be able to see the characters as you type them.

12) ffmpeg -f x11grab -s wxga -r 25 -i :0.0 -sameq /tmp/out.mpg
Capture video of a linux desktop

11) > file.txt
Empty a file
For when you want to flush all content from a file without removing it (hat-tip to Marc Kilgus).

10) $ssh-copy-id user@host
Copy ssh keys to user@host to enable password-less ssh logins.
To generate the keys use the command ssh-keygen

9) ctrl-x e
Rapidly invoke an editor to write a long, complex, or tricky command
Next time you are using your shell, try typing ctrl-x e (that is holding control key press x and then e). The shell will take what you’ve written on the command line thus far and paste it into the editor specified by $EDITOR. Then you can edit at leisure using all the powerful macros and commands of vi, emacs, nano, or whatever.

8 ) !whatever:p
Check command history, but avoid running it
!whatever will search your command history and execute the first command that matches ‘whatever’. If you don’t feel safe doing this put :p on the end to print without executing. Recommended when running as superuser.

7) mtr google.com
mtr, better than traceroute and ping combined
mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool.
As mtr starts, it investigates the network connection between the host mtr runs on and HOSTNAME. by sending packets with purposly low TTLs. It continues to send packets with low TTL, noting the response time of the intervening routers. This allows mtr to print the response percentage and response times of the internet route to HOSTNAME. A sudden increase in packetloss or response time is often an indication of a bad (or simply over‐loaded) link.

6 ) cp filename{,.bak}
quickly backup or copy a file with bash

5) ^foo^bar
Runs previous command but replacing
Really useful for when you have a typo in a previous command. Also, arguments default to empty so if you accidentally run:
echo “no typozs”
you can correct it with
^z

4) cd –
change to the previous working directory

3):w !sudo tee %
Save a file you edited in vim without the needed permissions
I often forget to sudo before editing a file I don’t have write permissions on. When you come to save that file and get the infamous “E212: Can’t open file for writing”, just issue that vim command in order to save the file without the need to save it to a temp file and then copy it back again.

2) python -m SimpleHTTPServer
Serve current directory tree at http://$HOSTNAME:8000/

1) sudo !!
Run the last command as root
Useful when you forget to use sudo for a command. “!!” grabs the last run command.

source

That’s it people!

Make a Web Server, Under 100 Dollars

I am going to show you how to Create a Web Server using an awesome technology called Plug Computing This website is powered byWordpress and a Ubuntu LAMP server. I built it using a Marvell Sheeva plug.

Plug Computing is a new term coined by Marvell to describe a new form of server. The idea behind plug computing is to have a small, low power, always on server that connects to the local network and provides the user access to central services. To promote the new concept, Marvell created the SheevaPlug development kit. The “computer” itself is housed in a 4″x2.5″x2″ wall wart that plugs directly into any typical household AC outlet. The SheevaPlug was built with the following hardware:

  • Kirkwood series SoC with an embedded Marvell Sheeva (88F6281) CPU core running at 1.2Ghz.
  • 512 Mbytes of DDR2 memory.
  • 512 Mbytes of NAND Flash memory use for system boot and the OS filesystem.
  • USB 2.0 (480Mbps) running as HOST.
  • Gigabit ethernet connection to the cpu.
  • SDIO interface capable of using SDHC type SD memory cards.
  • Dual serial port for JTAG interface (used by openOCD and OS serial output)

The Sheeva Plug development kit comes with the following software and documentation:

  • U-Boot
  • Linux Support Package (LSP)
  • Ubuntu and Gentoo File System
  • Host Software Support Package for Linux and Windows
  • Schematics & Bill of Materials

The product brief is available here.

This is what I did:

I added an 8GB SD Chip formatted as swap space.

I also added a 20GB Jump Drive that I setup in the FSTAB to mount as /var/www/

There are a few ways of connecting to this device, you can connect via a Serial Connection or SSH

I plugged the machine into my network and it received its IP via DHCP

I could have logged into the router to see what IP it received but instead I ran this command

bebe@genesis:~$ sudo arp-scan -l

arp-scan is a command-line tool that uses the ARP protocol to discover and fingerprint IP hosts on the local network.

Once the scan provided me with an IP address I fired up putty and logged in.

the first command I ran was

bebe@genesis:~$ sudo tasksel install lamp-server

Your machine is now a LAMP server.

Now itś time to setup Virtual Host so you can run multiple sites from the one Plug

Apache2 has the concept of sites, which are separate configuration files that Apache2 will read. These are available in /etc/apache2/sites-available. By default, there is one site available called default this is what you will see when you browse to http://localhost or http://127.0.0.1. You can have many different site configurations available, and activate only those that you need.

As an example, we want the default site to be /home/user/public_html/. To do this, we must create a new site and then enable it in Apache2.

To create a new site:

  • Copy the default website as a starting point. sudo cp /etc/apache2/sites-available/default /etc/apache2/sites-available/mysite
  • Edit the new configuration file in a text editor “sudo nano” on the command line or “gksudo gedit”, for example: gksudo gedit /etc/apache2/sites-available/mysite
  • Change the DocumentRoot to point to the new location. For example, /home/user/public_html/
  • Change the Directory directive, replace <Directory /var/www/> to <Directory /home/user/public_html/>
  • You can also set separate logs for each site. To do this, change the ErrorLog and CustomLog directives. This is optional, but handy if you have many sites
  • Save the file

Now, we must deactivate the old site, and activate our new one. Ubuntu provides two small utilities that take care of this: a2ensite (apache2enable site) and a2dissite (apache2disable site).

bebe@genesis:~$ sudo a2dissite default && sudo a2ensite mysite

I also recommend

bebe@genesis:~$ sudo a2enmod mod_rewrite

Finally, we restart Apache2:

sudo /etc/init.d/apache2 restart

If you have not created /home/user/public_html/, you will receive an warning message

To test the new site, create a file in /home/user/public_html/:

echo '<b>Hello! It is working!</b>' > /home/user/public_html/index.html

Finally, browse to http://localhost/

Set mysql bind address

Before you can access the database from other computers in your network, you have to change its bind address. Note that this can be a security problem, because your database can be accessed by others computers than your own. Skip this step if the applications which require mysql are running on the same machine.

type:

nano /etc/mysql/my.cnf

and change the line:

bind-address           = localhost

to your own internal ip address e.g. 192.168.1.20

bind-address           = 192.168.1.20

If your ip address is dynamic you can also comment out the bind-address line and it will default to your current ip.

If you try to connect without changing the bind-address you will recieve a “Can not connect to mysql error 10061”.

Set mysql root password

Before accessing the database by console you need to type:

mysql -u root

At the mysql console type:

mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('yourpassword');

A successful mysql command will show:

Query OK, 0 rows affected (0.00 sec)

Mysql commands can span several lines. Do not forget to end your mysql command with a semicolon.

Note: If you have already set a password for the mysql root, you will need to use:

mysql -u root -p

Create a mysql database

mysql> CREATE DATABASE database1;

Create a mysql user

For creating a new user with all privileges (use only for troubleshooting), at mysql prompt type:

mysql> GRANT ALL PRIVILEGES ON *.* TO 'yourusername'@'localhost' IDENTIFIED BY 'yourpassword' WITH GRANT OPTION;

For creating a new user with fewer privileges (should work for most web applications) which can only use the database named “database1”, at mysql prompt type:

mysql> GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES ON database1.* TO 'yourusername'@'localhost' IDENTIFIED BY 'yourpassword';

yourusername and yourpassword can be anything you like. database1 is the name of the database the user gets access to. localhost is the location which gets access to your database. You can change it to ‘%’ (or to hostnames or ip addresses) to allow connections from every location (or only from specific locations) to the database. Note, that this can be a security problem and should only be used for testing purposes!

To exit the mysql prompt type:

mysql> \q

Since the mysql root password is now set, if you need to use mysql again (as the mysql root), you will need to use:

mysql -u root -p

and then enter the password at the prompt.

Backup-Settings

Please, let’s say something in which directories mysql stores the database information and how to configure a backup

Alternatively

There is more than just one way to set the mysql root password and create a database. For example mysqladmin can be used:

mysqladmin -u root -p password yourpassword

and

mysqladmin -u root -p create database1

mysqladmin is a command-line tool provided by the default LAMP install.

So now you can download WordPress, Joomla, Drupal or create a site using any way you know how and place it in the /home/user/public_html/ folder
now all thatś left is to buy a domain name and point your website to your IP Address @ home and don´t forget to forward the ports on your router or modem to your switches IP..
Now you are good to go.