Variables

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Variables

The HPCC cluster uses bash as the default shell environment. Within this environment, variables can be set and reused.

For example:

MYVAR=’Something’
export MYVAR=’Something’
echo $MYVAR

Default Variables

Some softwares utilize this feature and require that specific environment variables be set. For example, every time you login, the following variables are set by default:

echo $HOME               #Contains your home path
echo $USER               #Contains your username
echo $PATH               #Contains paths of executables
echo $LD_LIBRARY_PATH    #Contains paths of library dependencies

Finding Variables

To see a list of all variables currently set in your shell, use the env command. You can also grep through this list to find variables, like so:

env | grep -i home

Or if you are in a Slurm job, you can find all related Slurm variables:

env | grep -i slurm

Setting variables

Try to choose unique names when setting variables. It is best to not overwrite a variable that is already set, unless on purpose.

To set a variable in your current shell, you can do so like this:

MYVAR='Something Important'

Notice that there is no spaces around the = sign.

If you would like to set a variable that is carried over to all other commands or sub-shells, then it must be exported:

export MYVAR='Something Important'