bash compare a string vs a list of strings

Question

Suppose I have the following code in bash:

#!/bin/bash

bad_fruit=( apple banana kiwi )
for fname in `ls`
do
  # want to check if fname contains one of the bad_fruit
  is_bad_fruit=??? # <------- fix this line
  if [ is_bad_fruit ]
  then
    echo "$fname contains bad fruit in its name"
  else
    echo "$fname is ok"
  fi
done

How do I fix is_bad_fruit so that it is true if fname contains one of the bad_fruit strings?

Answer 1

Another option (using grep with an inner loop and evaluating the exit code):

#!/bin/bash

bad_fruit=( apple banana kiwi )
for fname in *; do
  for fruit in "${bad_fruit[@]}"; do
    echo "$fruit"
  done | grep "$fname"
  if [ $? -eq 0 ]; then
    echo "$fname contains bad fruit in its name"
  else
    echo "$fname is ok"
  fi
done

Answer 2

Try the following code :

#!/bin/bash

bad_fruit=( apple banana kiwi )
re="$(printf '%s\n' "${bad_fruit[@]}" | paste -sd '|')"

for fname in *; do
  # want to check if fname contains one of the bad_fruit
  if [[ $fname =~ $re ]]; then
    echo "$fname contains bad fruit in its name"
  else
    echo "$fname is ok"
  fi
done

Take care of useless use of ls

ls is a tool for interactively looking at file information. Its output is formatted for humans and will cause bugs in scripts. Use globs or find instead. Understand why : http://mywiki.wooledge.org/ParsingLs