\\ \\\\ \\\\ \\\\\\ \\\\ \\\\\\ \\\\\\
\\\\ \\\\\\\\ \\ \\ \\\\\\\\ \\\\ \\
\\ \\ \\ \\ \\ \\\\ \\
\\ \\\\\\ \\\\\\ \\\\\\ \\\\\\ \\\\\\
\\
\\\\
regesc takes in a string from stdin and prints out an \escaped version, for use as a regular expression. This is useful if you have text containing a lot of special regex characters and wish to escape all of them so that your string can be used as a "literal" regex string, or be ready for modifications into a more complex regex, without having to manually escape everything yourself.
$ regesc
/he\\o! this i$ a rea||y (bad) [string] t+o ^USE? as {1} regu*lar e><pression.
\/he\\\\o! this i\$ a rea\|\|y \(bad\) \[string\] t\+o \^USE\? as \{1\} regu\*lar e><pression\.
^D
or, if from a file:
regesc < infile > outfile