Bash script to remove leading indent from code snippets.

remove-leading-indent.sh

#!/usr/bin/env bash

# Read lines from stdin into array:

lines=()

while IFS= read -r line; do
    lines+=("$line")
done

# Find minimum indentation level:

min_indent=0
first_non_empty=true

for line in "${lines[@]}"; do
    # Skip lines that are empty or only contain whitespace.
    if [[ -z "$line" || "$line" =~ ^[[:space:]]*$ ]]; then
        continue
    fi

    leading_whitespace=$(echo "$line" | sed -E 's/^([[:space:]]*).*$/\1/')
    indent=${#leading_whitespace}

    if [[ "$first_non_empty" = true || $indent -lt $min_indent ]]; then
        min_indent=$indent
        first_non_empty=false

        # If there's no indentation, we're done.
        if [[ $min_indent -eq 0 ]]; then
            break
        fi
    fi
done

# Remove minimum indentation from all lines:

for line in "${lines[@]}"; do
    if [[ -z "$line" ]]; then
        echo ""
    elif [[ "$line" =~ ^[[:space:]]*$ ]]; then
        echo "$line"
    else
        echo "${line:$min_indent}"
    fi
done