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while - Content

1. 1. Arithmetic
2. 2. filesystem-related conditions
3. 3. or for reading input
4. 4. Elegant endless loop
5. 5. Modify variable inside a while loop

while

1. Arithmetic

while (( COUNT < MAX ))
do
    some stuff
    let COUNT++
done

2. filesystem-related conditions

while [ -z "$LOCKFILE" ]
do
    some things
done

3. or for reading input

You can pass standard output to these lines:

while read lineoftext
do
    process $lineoftext
done

4. Elegant endless loop

Uff really elegant

while : ## Elegant Endless loop
do
    echo "Do something"
done

5. Modify a variable inside a while loop

#/bin/bash

# Inside while loop will not be modified variable movie
echo "First time"
movie=""
echo ${movie}
cat movies.txt | cut -d "." -f 2 | while read movie_name; do
  if echo "${movie_name}" | grep "Kid"; then
    movie="${movie_name}"
  fi
done
echo "${movie}"

echo "Second time"
while IFS= read -r movie_name; do
  if echo "${movie_name}" | grep "Kid"; then
    movie="${movie_name}"
  fi
done < movies.txt