Unix. Parse file with full paths to SHA256 checksums files. Run command in each path/file

Question

I have a file file.txt with filenames ending with *.sha256, including the full paths of each file. This is a toy example:

file.txt:

/path/a/9b/x3.sha256
/path/7c/7j/y2.vcf.gz.sha256
/path/e/g/7z.sha256

Each line has a different path/file. The *.sha256 files have checksums.

I want to run the command "sha256sum -c" on each of these *.sha256 files and write the output to an output_file.txt. However, this command only accepts the name of the .sha256 file, not the name including its full path. I have tried the following:

while read in; do
    sha256sum -c "$in" >> output_file.txt    
done < file.txt

but I get:

"sha256sum: WARNING: 1 listed file could not be read"

which is due to the path included in the command.

Any suggestion is welcome

Answer 1

#!/bin/bash

while read in
do
    thedir=$(dirname "$in")
    thefile=$(basename "$in")
    cd "$thedir"
    sha256sum -c "$thefile" >>output_file.txt
done < file.txt

Modify your code to extract the directory and file parts of your in variable.