Three spellings of the same command line

Answer

cut -d: -f 1 /etc/passwd cut -d : -f 1 /etc/passwd cut -d: -f1 /etc/passwd

All three run identically. The space between an option and its option argument is optional, so `-d:`, `-d :`, `-f 1` and `-f1` are free choices of style — not different commands.

Sarwar & Koretsky 3e ch2 §2.2