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  • chmod命令(chmod函数)自动清除设置用户ID位和设置组ID位

    《UNIX环境高级编程(第2版)》 4.9节

    1.chmod自动清除“设置组ID位”
    user3@SuSE11SP2-1:/home/user1/setgid> id
    uid=1003(user3) gid=1003(group3) groups=1003(group3),16(dialout),33(video)
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> ls -ld .
    drwxr-srwx 2 user1 users 4096 Mar 20 12:40 .
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> mkdir base_user3
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> ls -ld base_user3/
    drwxr-sr-x 2 user3 users 4096 Mar 20 12:40 base_user3/    # 设置组ID位生效,并且创建的目录继承了该位
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> mkdir base_user3/sub_user3
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> ls -ld base_user3/sub_user3/
    drwxr-sr-x 2 user3 users 4096 Mar 20 12:41 base_user3/sub_user3/    # 继承的“设置组ID位”生效
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> chmod o-x base_user3/
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> ls -ld base_user3/
    drwxr-xr-- 3 user3 users 4096 Mar 20 12:41 base_user3/    # 设置组ID位被自动关闭了
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> mkdir base_user3/sub_user3.new
    user3@SuSE11SP2-1:/home/user1/setgid>
    user3@SuSE11SP2-1:/home/user1/setgid> ls -l base_user3/
    total 8
    drwxr-sr-x 2 user3 users  4096 Mar 20 12:41 sub_user3
    drwxr-xr-x 2 user3 group3 4096 Mar 20 12:42 sub_user3.new
    user3@SuSE11SP2-1:/home/user1/setgid>

    2.写文件时,自动清除“设置用户ID位”
    user3@SuSE11SP2-1:/home> ls -l setuid.txt
    -rwSr--rw- 1 root root 0 Mar 20 13:05 setuid.txt
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> echo "hello" >setuid.txt
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> ls -l setuid.txt
    -rw-r--rw- 1 root root 6 Mar 20 13:07 setuid.txt    # 设置用户ID位被清除
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> ls -l setgid.txt
    -rw-r-Srw- 1 root root 0 Mar 20 13:07 setgid.txt
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> echo "hello" >setgid.txt
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> ls -l setgid.txt
    -rw-r-Srw- 1 root root 6 Mar 20 13:08 setgid.txt    # 设置ID位未被清除
    user3@SuSE11SP2-1:/home>
    user3@SuSE11SP2-1:/home> cat setgid.txt
    hello
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  • 原文地址:https://www.cnblogs.com/custa/p/2972416.html
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