Python构建脚本时使用的distutils库中的build_scripts模块：first_line_re函数介绍

The build_scripts module in the distutils library is used to build scripts in Python. One of the functions available in this module is first_line_re. This function is used to parse the shebang line (the first line of a script) and extract information such as the interpreter and any command line options specified.

The first_line_re function takes a string (the content of the script) as input and returns a match object if the shebang line matches a specified regular expression pattern. Otherwise, it returns None. Here is an example of how to use this function:

import re
from distutils import build_scripts

script_content = '''
#!/usr/bin/env python -O

# This is a sample script

print("Hello, World!")
'''

pattern = r'^#!\s*(?P<interpreter>\S+)(\s+(?P<options>.*))?$'
match = build_scripts.first_line_re(script_content, re.IGNORECASE)

if match:
    interpreter = match.group('interpreter')
    options = match.group('options')
    
    print(f'Shebang line matched: {match.group(0)}')
    print(f'Interpreter: {interpreter}')
    print(f'Options: {options}')
else:
    print('Shebang line not found or does not match the pattern.')

In this example, we have a sample script with a shebang line (#!/usr/bin/env python -O) followed by some Python code. We define a regular expression pattern that matches this specific shebang line format, where the interpreter is followed by any number of command line options.

We pass the script content and the regular expression pattern to the first_line_re function. If the shebang line matches the pattern, the function returns a match object. We can then use this match object to extract the interpreter and options from the shebang line.

In this case, the output will be:

Shebang line matched: #!/usr/bin/env python -O
Interpreter: /usr/bin/env
Options: python -O

This example demonstrates how the first_line_re function can be used to parse the shebang line of a script and extract information from it. It's particularly useful when building or installing scripts as part of a larger Python package or distribution.