Faster bash writing to file

Question

I'm reading a file in bash, taking the values out and saving them to another file. The file has ~100k lines in it, and it takes around 25minutes to read and rewrite them all.

Is there maybe some faster way to write to a file, because now I'm just iterating through the lines, parsing some values and saving them like this:

while read line; do
   zip="$(echo "$line" | cut -c 1-8)"
   echo $zip
done < file_one.txt

Everything works fine, the values are parsed correctly, I just want to know how can I optimize the process (if I even can).

Thanks

Answer 1

The bash loop only slows it down (especially the part where you invoke an external program (cut) once per iteration). You can do all of it in one cut:

cut -c 1-8 file_one.xt