Get file globs from a file and find these files

Question

I have a file called "file.txt" and it contains globs. Contents:

*.tex
*.pdf
*C*.png

I need to get these extensions from the file and then find the files containging these globs in the current directory (preferably using find, anything else is fine too).

I used

grep "" file.txt | xargs find . -name

but I get this error:

find: paths must precede expression: `*.pdf'

Using Ubuntu

Use `xargs -n 1` to prevent it from running `find . -name '*.pdf' '*.txt' '*.whatever'`, putting as many expressions as will fit after `-name` instead of just one. — Charles Duffy, Jul 28 '21 at 00:56
How else would I read the contents of the file and redirect them into xargs — Arzaan Ul, Jul 28 '21 at 01:08
Oh okay. Won't i also have to change the delimiter to '"\n"? — Arzaan Ul, Jul 28 '21 at 01:22
It's a good idea, but you have that problem with or without `grep`. The output of `grep` contains newlines just as much as the file itself does. — Charles Duffy, Jul 28 '21 at 02:20
But yes, in general, `xargs -d $'\n'` has fewer problems than xargs has without `-d`. — Charles Duffy, Jul 28 '21 at 02:39

score 4 · Accepted Answer · answered Jul 28 '21 at 00:58

The original code needs the -n 1 argument to be passed to xargs, to pass only one glob to each copy of find, as each glob expression needs to be preceded with a -name (and attached to any other -name expressions with -o, the "or" operator).

More efficient is to run find just once, after constructing an expression that puts all your -name operators on a single command line, separated with -os.

#!/usr/bin/env bash
#              ^^^^- MUST be run with bash, not /bin/sh

find_expr=( -false )
while IFS= read -r line; do
  find_expr+=( -o -name "$line" )
done <file.txt

find . '(' "${find_expr[@]}" ')' -print

The question restricts me to use a one liner so -n 1 worked. Thankyou :) — Arzaan Ul, Jul 28 '21 at 01:11

Get file globs from a file and find these files

1 Answers1