You can cat a file and pipe it to a while loop in order to perform a command in each line in the file.
cat [filename] | while read line; do [command] "$line"; done
For example, if you have a text file, called filenames.txt, that contains line-separated filenames...
file1.txt testdir/file2.txt file3.txt
...you can do the following to run 'ls -l' on each filename in filenames.txt:
steph@slap ~/tmp/test $ cat filenames.txt | while read line; do ls -l "$line"; done -rw-r--r-- 1 steph users 22 Sep 19 12:55 file1.txt -rw-r--r-- 1 steph users 22 Sep 19 12:55 testdir/file2.txt -rw-r--r-- 1 steph users 22 Sep 19 12:55 file3.txt
Or output their contents:
steph@slap ~/tmp/test1 $ cat filenames.txt | while read line; do cat "$line"; done Contents of file1.txt Contents of file2.txt Contents of file3.txt
