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Bash Scripting Loops

Bash scripting with loops

Mark Lucernas
2020-08-09

Loops

Looping Over Lines in a Variable String

list="One\ntwo\nthree\nfour"

while IFS= read -r line; do
  echo "$line"
done <<< "$list"

# or

echo "$list" | while IFS= read -r line; do
  echo "$line"
done

# or

for line in $(echo ${list}); do
  echo "$line"
done

For variables with literal string

echo -e "$list" | while IFS= read -r line; do
  echo "$line"
done

Ref:

Looping Over Filtered File Path Returned by Find

Method 1:

find . -name '*.txt' - print0 |
  while IFS= read -r -d '' file; do
    # do something with "$file"
  done

NOTE: Each command of a pipeline is executed in a separate subshell. So variables outside of the loop that are modified inside of the subshell will not change the value of the variables outside.

Method 2: (Recommended)

while IFS= read -r -d '' file; do
  # do something with "$file"
done < <(find . -name '*.txt' - print0)

This method allows for variable modification outside of the loop. See process substitution.

Ref:


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