Grep Shell Scripting: How do I Count the Number of Occurrences of Each Substring?
grep, shell
Solution
You could use `sort` and `uniq -c`:
$ grep -orE 'foo:(.*)' * | sort | uniq -c
2 foo:bar
1 foo:baz
Problem
Stack Overflow already has some great posts about counting occurrences of a string (eg. "foo"), like this one: count all occurrences of string in lots of files with grep. However, I've been unable to find an answer to a slightly more involved variant. Let's say I want to count how many instances of "`foo:[*whatever*]*whatever else*`" exist in a folder; I'd do: ``` grep -or 'foo:[(.*)]' * | wc -l ``` and I'd get back "55" (or whatever the count is). But what if I have a file like: ``` foo:bar abcd foo:baz efgh not relevant line foo:bar xyz ``` and I want to get count how many instances of `foo:bar` vs. how many of `foo:baz`s, etc.? In other words, I'd like output that's something like: ``` bar 2 baz 1 ``` I assume there's some way to chain `grep`s, or use a different command from `wc`, but I have no idea what it is ... any shell scripting experts out there have any suggestions? P.S. I realize that if I knew the set of possible sub-strings (ie. if I knew there was only "foo:bar" and "foo:baz") this would be simpler, but unfortunately there set of "things that can come after `foo:`" is unknown.