I agree with the comments above - learn shell scripting first.
chris webster wrote:... and PHP is only useful for web applications
PHP works quite well from the command line, and you can do admin work with it. However I don't know of any admins who grab it as their tool of choice.
Paul Santa Maria wrote:... bash (which has all the bells and whistles, but is Linux specific)
is the shell used by default in Linux systems, but it is GNU
software, not Linux specific software. It is also the default shell on a number of other operating systems, including Macintosh OS. For what it is worth, I don't remember an OS that I have used in the last 10 years that I have not used Bash on (including Windows 95, NT, 2000, XP; AIX, HPUX, VOS, FTX, ...)
Personally I use awk for a lot of my scripting, simply because when I first started using Unix systems, awk was always installed, but Perl was not guaranteed. Plus it is very C like. However if I were to start over, I would learn shell scripting first, then learn Perl.