A lot of information is available about individual files on a Unix system. For example, the ls -l command ... or retrieve one of the attributes in a script, one of the versatile tools is a command ...

Nohup is a command which prevents commands / scripts from stopping should we close a terminal window / SSH session.

is the name of a UNIX command, executable program, or shell script ... For example, if the fileref is used in an INFILE statement, then the SAS System assumes that the input comes from a UNIX command; ...