UNIX for Dummies Questions & Answers

I'm looking to determine if I can use a grep command to read file and rename the file based on the first 3 characters of the data in the file.

An example is:

Read FileA
If the first 3 positions of the data in the file are "ITP", then rename the file as FileA_ITP, else if the first 3 positions are "UNB" then rename the file FileA_UNB.

I believe I might be able to use the GREP command to identify the data but not sure how to rename the file being processed.

Appreciate any feedback.

Assuming you want to rename all the files in the current directory:

Code:

#!/bin/sh

for file in *; do
  ext=`cut -c 1-3 ${file}`
  mv ${file} ${file}_${ext}
done

Regards

Rather than using the cut utility, the shell builtin read could be used i.e.

Code:

for file in *; do
    read -r -n 3 ext < ${file}
    mv ${file} ${file}_${ext}
done

Which shell's built-in is that ?

Not working in zsh though