else
is a keyword that's found as part of if
and unless
statements.
perl -wnl -e "if (/^#/) { print } else { exit }" file.vcf
perl -wnl -e "/^#/ ? print : exit" file.vcf
perl -wnl -e "/^#/ or exit; print" file.vcf
perl -wpl -e "/^#/ or exit" file.vcf
perl -wpl -e "/^#/ or last" file.vcf
perl -p -e "/^#/ or last" file.vcf
perl -pe"/^#/ or last" file.vcf