Run A Command Line Process On All Files In A Directory And Collect The Output Into A New File

The Script

This was a test script for setting up a larger process. It reads all the files in a directory, passes them through a secondary process, then puts all the outputs in a single file :

bash

#!/bin/bash

OUTPATH="results file.txt"
: > "$OUTPATH"

for file in input_dir/*.txt
do
  cat "$file" \
  | tr '[:upper:]' '[:lower:]' \
  >> "$OUTPATH" 
done

Details

Using quotes around [TODO: Code shorthand span ] allows spaces in the path
The first ` : > "$OUTPATH" [TODO: Code shorthand span ] line clears out the file. From the bash manual, the ` : [TODO: Code shorthand span ] "Do nothing beyond expanding arguments and performing redirections. The return status is zero." When you point that to a file with ` > [TODO: Code shorthand span ] it clears it out
This version uses a ` for [TODO: Code shorthand span ] loop. I've seen other stuff that uses ` file [TODO: Code shorthand span ] but haven't explored the differences yet
The meat of the program runs ` cat [TODO: Code shorthand span ] on each file to output it then pipes that output to ` tr [TODO: Code shorthand span ] with ` PIPE _ HERE ` bash ` before appending it to the output file via ` > > ` bash `
The ` tr [TODO: Code shorthand span ] command changes all upper case letters to lowercase
Any command that works in the pipeline can be used in place of ` tr ` bash ` . It's simply what's being used for the illustration

Example

Given these three input files :

code fullcode fullcode full

The script will produce :

results full

Run A Command Line Process On All Files In A Directory And Collect The Output Into A New File

The Script

Details

Example

Footnotes And References