I want to write a shell script. I list my jpg files inside nested subdirectories with the following command line:
find . -type f -name "*.jpg"
How can I save the output of this command inside a variable and write a for loop for that? (I want to do some processing steps for each jpg file)
You don't want to store output containing multiple files into a variable/array and then post-process it later. You can just do those actions on the files on-the-run.
Assuming you have bash shell available, you could write a small script as
#!/usr/bin/env bash
# ^^^^ bash shell needed over any POSIX shell because
# of the need to use process-substitution <()
while IFS= read -r -d '' image; do
printf '%s\n' "$image"
# Your other actions can be done here
done < <(find . -type f -name "*.jpg" -print0)
The -print0 option writes filenames with a null byte terminator, which is then subsequently read using the read command. This will ensure the file names containing special characters are handled without choking on them.
Better than storing in a variable, use this :
find . -type f -name "*.jpg" -exec command {} \;
Even, if you want, command can be a full bloated shell script.
A demo is better than an explanation, no ? Copy paste the whole lines in a terminal :
cat<<'EOF' >/tmp/test
#!/bin/bash
echo "I play with $1 and I can replay with $1, even 3 times: $1"
EOF
chmod +x /tmp/test
find . -type f -name "*.jpg" -exec /tmp/test {} \;
find . -type f -name "*.jpg" | head -n 10 | xargs -n1 command
(this another solution doesn't take care of filenames with newlines or spaces)
This one take care :
#!/bin/bash
shopt -s globstar
count=0
for file in **/*.jpg; do
if ((++count < 10)); then
echo "process file $file number $count"
else
break
fi
done
