Search, Count, and Sort File Matches using Regular Expression

Search for and analyze the occurrences of a specified regular expression within files located in the current directory and its subdirectories. Organize and present the results by counting the occurrences in each file and sorting them in descending order of count.

Using grep, awk and sort to achieve this.

grep -Erc '[fF]oobar' . | awk -v FS=":" -v OFS="\t" '$2>0 { print $2, $1 }' | sort -hr

First part: grep

https://man7.org/linux/man-pages/man1/grep.1.html

• E - Use extended regular expressions (ERE) instead of basic ones (BRE)
• r - Read all files under each directory, recursively
• c - Suppress normal output; instead print a count of matching lines for each input file.

Example output:

./docs/index.md:3
./docs/misc/unix-time.md:2
./docs/misc/deployment.md:0
./docs/misc/ssh-add-startup.md:0
./docs/misc/editorconfig-naming-convention.md:7
./docs/misc/find-delete-files.md:1

Second part: awk

https://man7.org/linux/man-pages/man1/awk.1p.html

awk is going to filter out files with 0 matches and change the structure of the output from <file>:<matches> to <matches>tab<file>.

• -v FS=":" - This is creating a variable called FS and assigning the value : to it.
• -v OFS="\t" - This is creating a variable called OFS and assigning the value \t to it.
• '$2>0 { print $2, $1 }' - Print every line where the 2nd column $2 is greater than 0. First print the 2nd column and then the 1st column.

Example output:

3 ./docs/index.md
2 ./docs/misc/unix-time.md
7 ./docs/misc/editorconfig-naming-convention.md
1 ./docs/misc/find-delete-files.md

More Info and Alternatives

-v var=val
--assign var=val
Assign the value val to the variable var, before execution of the program begins. Such variable values are available to the BEGIN block of an AWK program.

The following awk commands produce the same result.

awk 'BEGIN{FS=":"; OFS="\t"} $2>0 { print $2, $1 }'
awk -F: '$2>0 { print $2 "\t" $1 }'

Third part: sort

https://man7.org/linux/man-pages/man1/sort.1.html

Default behavior of sort command is to sort by the first column/field/key whatever you wanna call it. The default field separator is a blank space. awk returns a tab delimited string the whole thing seems to work either way ¯\_(ツ)_/¯

• h - Human readable
• r - Default is ascending, this option reverses the order so the output is sorted in descending order.

Final Result

So the command grep | awk | sort produces a result that looks something like this:

7 ./docs/misc/editorconfig-naming-convention.md
3 ./docs/index.md
2 ./docs/misc/unix-time.md
1 ./docs/misc/find-delete-files.md