如何编写bash函数isInRequiredFormat校验指定格式字符串？

To check if a string follows the exact format exerciseNumber{N}Published (where {N} is a natural number), you can use bash's built-in regular expression matching with the [[ ... =~ ... ]] operator. Here's a practical, easy-to-use implementation:

The isInRequiredFormat Function #

This function takes a single string argument and returns 0 (success) if it matches the required format, or 1 (failure) otherwise. By default, we assume natural numbers are positive integers (1, 2, 3, ...)—see the note below if you need to include zero.

isInRequiredFormat() {
    # Make sure exactly one input string is provided
    if [ $# -ne 1 ]; then
        echo "Error: Please pass exactly one string to validate." >&2
        return 1
    fi

    # Regex breakdown:
    # ^ = start of string (ensures no extra characters before the pattern)
    # exerciseNumber = literal fixed prefix
    # [1-9][0-9]* = positive natural number (starts with non-zero digit, followed by any number of digits)
    # Published = literal fixed suffix
    # $ = end of string (ensures no extra characters after the pattern)
    local pattern='^exerciseNumber[1-9][0-9]*Published$'

    # Run case-sensitive regex match
    if [[ "$1" =~ $pattern ]]; then
        return 0  # String is in valid format
    else
        return 1  # String does NOT match the format
    fi
}

Key Notes #

• Exact Match Guarantee: The ^ and $ anchors ensure the entire string must fit the pattern—no partial matches or extra characters allowed.
• Natural Number Flexibility: If you consider 0 a valid natural number here, replace the regex pattern with ^exerciseNumber[0-9]+Published$ (this allows one or more digits, including zero).
• Case Sensitivity: Bash regex is case-sensitive by default, so this function will only match strings with exact casing (exerciseNumber with a capital N, Published with a capital P).

Usage Examples #

Test the function with valid and invalid inputs to see how it works:

# Valid test cases
isInRequiredFormat "exerciseNumber1Published" && echo "Valid" || echo "Invalid"  # Output: Valid
isInRequiredFormat "exerciseNumber42Published" && echo "Valid" || echo "Invalid"  # Output: Valid
isInRequiredFormat "exerciseNumber1000Published" && echo "Valid" || echo "Invalid"  # Output: Valid

# Invalid test cases
isInRequiredFormat "exerciseNumber0Published" && echo "Valid" || echo "Invalid"  # Output: Invalid (using positive natural number pattern)
isInRequiredFormat "ExerciseNumber1Published" && echo "Valid" || echo "Invalid"  # Invalid (capital E)
isInRequiredFormat "exerciseNumberPublished" && echo "Valid" || echo "Invalid"  # Invalid (missing number)
isInRequiredFormat "exerciseNumber123published" && echo "Valid" || echo "Invalid"  # Invalid (lowercase p)
isInRequiredFormat "fooexerciseNumber1Publishedbar" && echo "Valid" || echo "Invalid"  # Invalid (extra text at start/end)

内容的提问来源于stack exchange，提问作者AskMath