Robust Scripts

Reading Lines

Preserving Text

Line-oriented scripts need to keep the text exactly as it arrives. IFS= read -r is the usual safe loop shape.

Program

Play the script to watch two input lines update the loop variables without losing the embedded space.

read_lines.sh 
#!/usr/bin/env bash

count=0
last=""
while IFS= read -r line; do
  count=$((count + 1))
  last="$line"
done <<'DATA'
alpha
two words
DATA
echo "$count:$last"
read -r `read -r` reads a line without treating backslashes as escape characters.
IFS= `IFS=` keeps leading and trailing whitespace from being trimmed before assignment.
here document `<<'DATA'` feeds literal lines to the loop until the closing marker.