Multiple choice technology operating systems

The /etc/passwd file does not have write permission for others and group. Still the non root users when use the command 'passwd' are actually updating the /etc/passwd file . How does unix allow this?

  1. Because of the principle of SUID

  2. Because the passwd command lies in /usr/bin

  3. /etc/passwd is a special file and so it is allowed

  4. None of these
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A Correct answer
Explanation

The passwd command has the SUID (Set User ID) bit set, which allows it to execute with root privileges temporarily. When a non-root user runs passwd, the program runs as root and can therefore modify /etc/passwd even though normal users lack write permission. This is a standard Unix security mechanism for privileged operations.

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