Linux command line

The IQ HPC Platform, Alliance clusters, and all supercomputers in the TOP500 use the Linux operating system. You need basic knowledge of the Linux/UNIX command line to use almost any high performance computing system.

If you are not already familiar with Linux or if you wish to refresh your memory, we highly recommend the Calcul Québec training. If no training is available soon, feel free to contact our technical support for custom local training. Finally, the Alliance technical documentation offers a short Linux introduction.

Linux quick reference

Moving around

Basic commands to navigate the file system are shown in this table:

Command	Description
pwd	Give the absolute path of the current working directory
ls	List files and directories
cd <dir>	Go to directory <dir>
mv <orig> <dest>	Move or rename the <orig> file or directory to <dest>
cp <orig> <dest>	Copy the <orig> file to <dest>
cp -r <orig> <dest>	Copy the <orig> directory and its contents to <dest>
rm <file>	Delete a file (be careful! this is definitive, there is no trash)
rm -r <dir>	Delete a directory and its contents (be careful! this is definitive, there is no trash)

Note that ./ represents the current working directory. For instance, cd ./ goes to the current directory (i.e. nothing changes), and cp folder1/foo.txt ./ copies foo.txt from folder1 to the current directory. Similarly, ../ represents the parent directory. For instance, cd .. goes to the parent directory. Finally, ~ represents your home directory, your initial location when you connect with SSH.

Editing ASCII files

Command	Description
cat <file>	Show the content of <file>
head -n X <file>	Show the first X lines of <file>
tail -n X <file>	Show the last X lines of <file>
less <file>	Browse the content of <file> (type q to quit)
touch <file>	Create an empty file named <file>
nano <file>	Open <file> in the Nano text editor. Type Crtl+O to save, Ctrl+X to quit