Useful Unix commands

Below you will find a list of some of the most frequently used commands when using LSNM in a Unix/Linux workstation. Please note that they are not meant to be exhaustive.

How to tar and zip a directory prior to copying or transferring:

$ tar -cvzf file_name.tar.gz directory_name

How to unpack and unzip a tar.gz file:

$ tar -xzvf file_name.tar.gz

How to download a file from remote server:

$ scp username@remote.server.com:/home/username/myfile .

How to upload a local file to remote server:

$ scp mylocalfile username@remote.server.com:/home/username

To run a GUI-based program remotely, you need to tunnel the X-windows connection through the SSH connection as follows:

$ ssh -X username@remote.server.com

After pressing <Enter>, you will have to provide your remote server password.

How to execute same command on a number of files using a unix (bash) script loop. Let's say we want to execute

the script 'netgen.py' on all files in current directory with extension 'ws':

$ for file in *.ws; do
$     python netgen.py $file
$ done

How to execute jobs in a remote server and log out without killing those jobs.

First, log in to the remote server using 'ssh' (see above), then execute the command 'screen' to open a virtual screen, then execute your command using 'nohup':

$ nohup python python_script.py &

Now you can disconnect from you screen typing <Ctrl><a><d>, which will disconnect you from the virtual screen. You can log out and later come back to the same virtual screen to check on your job(s) by typing:

$ screen -RD