Question

I’m (a regex noob) trying to find only the files in a directory that begin with numbers and not strings.

My regex is

 .*/^\d+\w+[A][D][0-5][0-9].mat

(The end of the file name has the letters AD and then numbers from 0-54 before the MAT extension. I include ./ because I am going to pass this to find in bash.)

However, this returns false for both files like

./times_121312_going_down_AD33.mat

and

./121312_going_down_AD33.mat

What am I doing wrong?

Answer 1

Here’s a working example with find

$ ls -l *.mat
-rw-r--r-- 1 root root 0 Jan 13 15:09 121312_going_down_AD33.mat
-rw-r--r-- 1 root root 0 Jan 13 15:09 times_121312_going_down_AD33.mat

$ find . -type f -regex '.*/[0-9]+_.*AD[0-5][0-9]\.mat$'
./121312_going_down_AD33.mat

\d and \w don’t work in POSIX regular expressions, you could use [:digit:] tho

The regular expression explained

• .* repeat any character except\n, zero or more times
• / match character ‘/’ literally
• [0-9]+ repeat any char in 0 to 9, one or more times
• _ match character ‘_’ literally
• .* repeat any character except\n, zero or more times
• A match character ‘A’ literally
• D match character ‘D’ literally
• [0-5] Match any char in 0 to 5
• [0-9] Match any char in 0 to 9
• \. match ‘.’ literally
• m match ‘m’ literally
• a match ‘a’ literally
• t match ‘t’ literally
• $ end of string

If you just want to match all files beginning with an integer you can break it down to .*/[0-9] which would also match ./12/test.tmp and ./12_not_a_mat_file.txt