Question

I want to execute a bash script on a list of text files (using a for loop, I guess), redirecting stdout to a file with the same path as the text file from stdin plus an extension (for example .txt or .sam, or just add a ~ to the end of the stdin path to make it different).

Answer 1

Okay, assuming the list isn’t too long, you can start with

  for i in `cat list`
  do
      # do stuff here
  done

If the list is long enough to risk a too-long command line, there’s a while variant

  cat list | while read i
  do
       # do stuff here
  done

you can construct the file name using basename(1) to get rid of the old extension suffix; for say .txt to .bak use

  `basename .txt ${i}`.bak

you can get the path part using dirname(1)

Since macros are expanded early, you can simply construct the command line in variables and expand them. Where op and np are your path names

   command < $op > $np

There’s a lovely on-line book, the bash Advanced Scripting Guide that covers this and more.