Update cheatsheets

perl

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# perl
+
+> The Perl 5 language interpreter.
+> More information: <https://www.perl.org>.
+
+- Print lines from `stdin` [m/] matching regex1 and case insensitive [/i] regex2:
+
+`perl -n -e 'print if m/{{regex1}}/ and m/{{regex2}}/i'`
+
+- Say [-E] first match group, using a regexp, ignoring space in regex [/x]:
+
+`perl -n -E 'say $1 if m/{{before}} (  {{group_regex}}  ) {{after}}/x'`
+
+- [-i]n-place, with backup, [s/] substitute all occurrence [/g] of regex with replacement:
+
+`perl -i'.bak' -p -e 's/{{regex}}/{{replacement}}/g' {{path/to/files}}`
+
+- Use perl's inline documentation, some pages also available via manual pages on Linux:
+
+`perldoc perlrun ; perldoc module ; perldoc -f splice; perldoc -q perlfaq1`