Compare file name to string in bash

Question

I'm creating a backup function to copy all files with an specific extension extension.

files() returns '*' '+' './' when it has not found file results, so I'm trying to avoid the invalid cp [* | + | ./] /backup with an if but it only works for *.

function backupByExt {
  # $1 = extension $2 = searchPaths $3 = backPath
  ext=$1
  sp=$2
  bp=$3
  files=( "$sp" + *."$ext" )
  # printf 'Backing up %s files: %d\n' "$ext" "${#files[@]}"
  # loop over all the files having the current extension
  for f in "${files[@]}"
  do
    # printf 'File: %s bp: %s\n' "$f" "$bp"
    if [ "$f" != "*" ] && [ "$f" != "+" ] && [ "$f" != "./" ]; then
      cp "$f" "$bp"
    fi
  done
}

What's Python got to do with this - did you mean to tag it as bash ? — Jon Clements
– Jon Clements, Commented Mar 11, 2018 at 16:10
The "linux" tag isn't correct either, as should be obvious from its description. — Ulrich Eckhardt
– Ulrich Eckhardt, Commented Mar 11, 2018 at 21:36

ensc · Accepted Answer · 2018-03-11 17:15:33Z

2

files=( "$sp" + *."$ext" )

looks wrong; the + will become the second element of the arrey. You probably want

files=( "$sp"/*."$ext" )

The check for != * can be omitted by shopt -s nullglob.

A case statement might be more readable than your || chain (which should be &&):

case $f in
  ./|\+|\*)  ;;
  *) cp "$f" "$bp/" ;;
esac

edited Mar 11, 2018 at 17:15

answered Mar 11, 2018 at 16:22

ensc

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2 Comments

Marco Rojas Over a year ago

'shopt -s nullglob' is equivalent to '+nullglob'?

ensc Over a year ago

yes; you are right. -s is correct; + does not work

Adi219 · Accepted Answer · 2018-03-11 16:11:44Z

You need to use && (and).

This is because you only want to print the file if the results are not *, + or ./. This means that you want to make sure all three of those conditions are False, and the way you do this is by using &&.

Currently, your code isn't working as it first checks if results are not equal to *. If this condition is True, there is no need to evaluate the other two conditions so bash will just go to the next line of code (ignoring your other conditions as you're using or).

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