Well, adding -Mstrict and qualifying every variable with my may be a little much for a one-liner. But adding a single -w? Consider:
2:05 >type nums.txt
1
2
3
4
2:05 >perl -nE "$sum += $_; END { say $sum }" nums.txt
10
2:06 >perl -nwE "$sum += $_; END { say $sum }" nums.txt
10
2:06 >perl -nE "$sum += $_; END { say $sun }" nums.txt
2:06 >perl -nwE "$sum += $_; END { say $sun }" nums.txt
Name "main::sum" used only once: possible typo at -e line 1.
Name "main::sun" used only once: possible typo at -e line 1.
Use of uninitialized value $sun in say at -e line 1, <> line 4.
2:06 >
That’s a lot of potential help for the cost of just one extra character on the command line. :-)
