$ cat data initial start interior end final $ # Include both endpoints $ perl -wlne'print if /start/../end/' data start interior end $ # Exclude starting point $ perl -wlne'print if ((/start/../end/) || 0) > 1' data interior end $ # Regex alternative for exclude starting point $ perl -wlne'print if (/start/../end/) =~ /^(?!1(?!\d))\d/' data interior end $ # Exclude ending point $ perl -wlne'print if (/start/../end/) =~ /^\d+$/' data start interior $ # Exclude both endpoints $ perl -wlne'print if (/start/../end/) =~ /^\d+(?