This is a useful oneliner that uses egrep to check on the status of a geometry optimisation. It is taken from Exploring chemistry with electronic structure methods: a guide to using Gaussian*, a very useful, albeit old, book about Gaussian 98. I usually copy the code below into a bash script, change its mode with chmod** and then place it in my personal script folder (which is indicated in my path). You could alternatively just put the egrep line as an alias in your shell profile.
egrep 'out of| SCF Don|Converged| NO |YES|exceeded' $file | grep -v '\\\\'
*Foresman, James B., and Æleen Frisch. Exploring chemistry with electronic structure methods: a guide to using Gaussian. Gaussian, 1993.