Finding gaps in sequential numbers

Question

I don’t do this stuff for a living so forgive me if it’s a simple question (or more complicated than I think). I‘ve been digging through the archives and found a lot of tip

Answer 1

Perl solution similar to awk solution from StardustOne:

perl -ane 'if ($F[0] != $p+1) {printf "%d-%d\n",$p+1,$F[0]-1}; $p=$F[0]' file.txt

These command-line options are used:

• -n loop around every line of the input file, do not automatically print every line

• -a autosplit mode – split input lines into the @F array. Defaults to splitting on whitespace. Fields are indexed starting with 0.

• -e execute the perl code