用一个小程序(argv.py)来演示下：
#!/usr/local/bin/python3 import sys print('sys.argv has these', len(sys.argv), 'elements:', sys.argv)
运行与结果：
# 首先是赋予执行权限 chmod 755 argv.py #1 一个空格一个命令行参数 ./argv.py I love Shell scripting. sys.argv has these 5 elements: ['./argv.py', 'I', 'love', 'Shell', 'scripting.'] #2 命令行所有参数被''或者""引起来变成一个字符串 ./argv.py 'I love Shell scripting.' sys.argv has these 2 elements: ['./argv.py', 'I love Shell scripting.'] ./argv.py "I love Shell scripting." sys.argv has these 2 elements: ['./argv.py', 'I love Shell scripting.'] #3 反引号内的执行结果成为命令行参数 ./argv.py `seq 1 5` sys.argv has these 6 elements: ['./argv.py', '1', '2', '3', '4', '5'] #4 被''引起来反引号内的内容不执行，整体直接变成一个字符串 ./argv.py '`seq 1 5`' sys.argv has these 2 elements: ['./argv.py', '`seq 1 5`'] #5 被""引起来，反引号内的执行结果变成一个字符串 ./argv.py "`seq 1 5`" sys.argv has these 2 elements: ['./argv.py', '1\n2\n3\n4\n5']
#6 变量作为命令行参数 a='I love Shell scripting.' ./argv.py $a sys.argv has these 5 elements: ['./argv.py', 'I', 'love', 'Shell', 'scripting.'] #7 被''引起来，a变量自身变成一个字符串 ./argv.py '$a' sys.argv has these 2 elements: ['./argv.py', '$a'] #8 被""引起来，输出a变量的内容 ./argv.py "$a" sys.argv has these 2 elements: ['./argv.py', 'I love Shell scripting.'] #9 类似3 ./argv.py $(seq 1 5) sys.argv has these 6 elements: ['./argv.py', '1', '2', '3', '4', '5'] #10 类似4 ./argv.py '$(seq 1 5)' sys.argv has these 2 elements: ['./argv.py', '$(seq 1 5)'] #11 类似5 ./argv.py "$(seq 1 5)" sys.argv has these 2 elements: ['./argv.py', '1\n2\n3\n4\n5']
