Shell script to get specific file names as string from particular directory which are modified before 1 day [closed]

Question

I written shell script to get names of all the files that start with a certain name, as well as all the files that have been edited within the previous day. These file names should be assigned to a single variable. I'm running below script on SUSE Linux 15.

DESTINATIONS="main_crontab"
#get all cron files
find . -name "sample_file_*" -type f -mtime -30 -print0 | while read -d $'\0' file
do  
    DESTINATIONS+=" ${file}"
done
echo ${DESTINATIONS} 

Directory Structure:
Folder_A > sample_file_xx.text (modified today)
Folder_A > sample_file_yy.text (modified today)
Folder_A > sample_file_xx.text (modified two days before)

Expected Output:
echo ${DESTINATIONS} # sample_file_xx.text sample_file_yy.text

Current Output:
echo ${DESTINATIONS} # sample_file_xx.text

Answer 1

The main problem is that the while loop, being part of a pipeline, is run in a subshell, and will set DESTINATIONS in the subshell that it's run in, not in the current shell.

In addition to that:

1. -mtime -30 will evaluate to true if the file's modification date is at most 30 days old, which is not what you want; you should change it to -not -mtime -1 (or -mtime +0 - although I find the former to be more eloquent in this case) to catch files whose modification date is at least 1 day old;
2. You should add IFS= and -r to your read command, to prevent filenames containing leading / trailing whitespace or backslashes, such as file.txt, file.txt or files.tx\t, from being mangled;
3. In general, you should avoid using all-caps names for variables.

A possible solution would be to run the while loop in the current shell, running the find command in a process substitution:

while IFS= read -r -d $'\0' file
do
    destinations+=" ${file}"
done < <(find . -name "sample_file_*" -type f -not -mtime -1 -print0)
echo ${destinations}