I want to make a script that puts filenames from the working directory (with a specific extension) in text file with some additional strings:

For example, if I'm interested in files with extension i and files in my directory are:

1.b  1.i  2.i  2.z 3.i

I want to make a text file like:

command_2 1.i 1.o && command_2 2.i 2.o && command_2 3.i 3.o &
  • Will the rest of the script be same? You just need the files of successive names from current directory to be replaced as the first arguments of the successions of command_2 ? – heemayl Apr 21 '15 at 19:02
  • yes, also I need put the same filename but with other extension ("o") as the second argument, and etc for the next file. – Gena Kozyukin Apr 21 '15 at 19:37
  • What is your final goal? Just making a text file in the exact format given or running commands ? – heemayl Apr 21 '15 at 21:42

I found a better solution.

Skip making a text file and just made a script to execute multiple files in a folder


for file in *.i*
  [[ "${file##*.}" =~ fchk ]] && continue
  qchem "$file" "${file%.*}".out 

echo "DONE!"

Considering your answer you don't really want to create a text file but just search for files and process them. You can use the find command for that, for example to rename all files ending in .i replacing i by o do:

find -maxdepth 1 -type f -name "*.i" -exec bash -c 'mv "$0" "${0/i/o}"' "{}" \;


  • -maxdepth 1 stay in the current directory
  • -type f search files only
  • -name "*.i" search files ending in .i
  • -exec execute the following command on the file, {} is substituted by the file name, needs to be finished with \;
  • bash -c start a subshell running the following commands, by adding "{}" we give it the filename as argument 0
  • mv "$0" "${0/i/o}" rename the file by substituting i by o – just an example of course, can be replaced by any (chain of) commands you like
  • \; finishes the -exec option

For commands that can take more than one file at a time you can substitute \; by + to chain the arguments, see What is the difference between using '+' (plus) and ';' (semicolon) in -exec command?.


An alternative if for some reason you want to use a file to store the list of files:

ls *.i  > input.txt
for F in $(cat /path/to/input.txt) ; do

or, if you have spaces in your filenames

while read F  ; do
done </path/to/input.txt

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