Linux Administration Cookbook

There's more...

Remember that you don't have to use the system's package manager to list versions; if you would rather trust the output of the application itself, most applications have some variation of the -v, --version standard.

bash, for example, is as follows:

$ bash --versionGNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)Copyright (C) 2011 Free Software Foundation, Inc.License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>This is free software; you are free to change and redistribute it.There is NO WARRANTY, to the extent permitted by law.

The following shows the code for ssh, which uses -V (uppercase):

$ ssh -VOpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017

And, just to be awkward, Vagrant uses ...