Mastering Linux Shell Scripting - Second Edition

Displaying user account data

The local user account database in Linux is the /etc/passwd file and this is readable by all user accounts. If we want to search for the line that contains our own data, we can use either our own login name in the search or use parameter expansion and the $USER variable. We can see this in the following command example:

$ grep "$USER" /etc/passwd 

In this example, the input to grep comes from the /etc/passwd file and we search for the value of the $USER variable. Again, in this case, it is a simple text, but it is still the regular expression, just without any operators.

For completeness, we include the output in the following screenshot:

We can extend this a little using this type of query as a condition within ...