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regex_stdin

What is the regex_stdin project about?

This is a General Purpose Tool that reads lines of text from Standard Input.
Lines that match the PCRE regular expression become eligible for output (multiple groups are allowed). Output is formatted with a "printf" formatting specification (similar to AWK, Perl, C),
with matched group value positional values passed to the printf spec in any order desired.

Make use of your Regular Expression super-powers!

How can regex_stdin be useful?

  • Allows data transformations with no extra programming.
  • Useful as an ad-hoc filter or data tranformation tool
  • Command output from a program can be piped into regex_stdin.pl to be filtered or transformed
  • Cat a file or use unix command pipe as input ... piped to regex_stdin.pl to be filtered or transformed
  • Send logging output through regex_stdin.pl to identify specifix error messages or other conditions that match a given regular expression
  • Used as part of a shell script for string transformations in variable assignments
  • Use printf_stdin.pl to generate custom commands based groups matched and the formatting specification
  • Use printf_stdin.pl as a tool for data profiling by extracting a specific group match that can then be passed to "| sort | uniq -c"
  • Use printf_stdin.pl to display the line numbers and full text where match occurred (NUMROWS)
  • Use printf_stdin.pl to display how many matches occurred (MATCHCOUNT)
  • Use printf_stdin.pl to display how many out of total number of rows that matched (MATCHSUMMARY)

Requirements for regex_stdin.pl ?

  • Very little at all.
  • Perl verion 5.xx is all that is required, which is normally on Unix, Linux, AIX by default.
    To get the version of perl... try:
    perl -v
  • regex_stdin.pl should work fine on MacOS if perl is installed.
  • regex_stdin.pl will work with Windows version that supports ActiveState Perl or Strawberry Perl (5.xx)
  • (Tested on versions of Perl ... 5.6 through 5.28)

Here are a few Regular Expression web sites that will come in handy for reference

regex_stdin.pl takes "regex" as the first parameter)

Examples Descr, Cmd, Output
match 4 paren groupings,

notice the group position numbers are passed to the format string in a different order		 Description:
grp1: (line begins with integer) space char
grp2: (the word "quick") space char
grp3: (1 or more non-space chars) space char
grp4: (remaining chars up to end of line) linefeed char

Cmd:
echo "22 quick brown foxes" | \
./regex_stdin.pl "^(/d+)\s(quick)\s(\S+)\s(.*)$" "%i %s %s and %s" 1 4 2 3

Output:
22 foxes quick and brown
example2 more docs to come