TEST
The command test allows two strings or two integers to be compared. A shorthand version uses [ and ] around the arguments. WARNING: be very careful to put the spaces in correctly! The syntax is very different for comparing numbers or strings (see help test for the syntax options). test can also be used to check the status of files (whether they exist, are writable, etc.)   test $a = my         string equality   [ $a = my ] as above   [ $a -eq 2 ] tests numerical equality   [ 11 -gt 2 ] compares numbers (greater than)   [ 11 > 2 ] does NOT do numerical comparison   [ -e im1.nii.gnii.gz ] tests if file exists     Note: for non-integer numerical comparisons, see bc