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Why would /etc/passwd be used every time someone executes `ls -l` command?

Why root's password change doesn't require old passwordFreeBSD create user without utility?Difference between ! vs !! vs * in /etc/shadowConditionally unlock a password, on a read-only filesystemWhat is the default SHA512 salt used in passwd and for the hash stored in the shadow file?Why the “ passwd ” command give the root shell without password?useradd command truncates the password mentioned with -p optionNo users can log inWhy passwd prohibits me from setting “simple” password?I want a normal user to change it's own password

4

Read from APUE, just feel curious:

The password file is used every time a user logs in to a
UNIX system and every time someone executes an ls -l command.

ls passwd

share|improve this question

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  FYI I try strace ls -l later on, I see a openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4 statement.
  
  – Rick
  26 mins ago
  
  
  

  
  
  
  

add a comment | 

4

Read from APUE, just feel curious:

The password file is used every time a user logs in to a
UNIX system and every time someone executes an ls -l command.

ls passwd

share|improve this question

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  FYI I try strace ls -l later on, I see a openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4 statement.
  
  – Rick
  26 mins ago
  
  
  

  
  
  
  

add a comment | 

Read from APUE, just feel curious:

The password file is used every time a user logs in to a
UNIX system and every time someone executes an ls -l command.

ls passwd

share|improve this question

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

share|improve this question

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

share|improve this question

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

edited 2 hours ago

Olorin

3,8681721

edited 2 hours ago

Olorin

3,8681721

asked 3 hours ago

RickRick

1335

asked 3 hours ago

RickRick

1335

1 Answer
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5

The file-system directly associates the numerical UID (User ID) and GID (Group ID) values with the file, not the user name and group name (which are strings). So the ls -l command (and any other command that displays the user and group owner of a file) need to get the user and group names from somewhere. The /etc/passwd file is one such source (probably the original and most common source). The manual bears this out - from PASSWD (5) (i.e. the man page for the /etc/passwd file):

many utilities, like ls(1) use it to map user IDs to usernames

share|improve this answer

edited 2 hours ago

answered 2 hours ago

igaligal

5,3711234

add a comment | 

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5

The file-system directly associates the numerical UID (User ID) and GID (Group ID) values with the file, not the user name and group name (which are strings). So the ls -l command (and any other command that displays the user and group owner of a file) need to get the user and group names from somewhere. The /etc/passwd file is one such source (probably the original and most common source). The manual bears this out - from PASSWD (5) (i.e. the man page for the /etc/passwd file):

many utilities, like ls(1) use it to map user IDs to usernames

share|improve this answer

edited 2 hours ago

answered 2 hours ago

igaligal

5,3711234

add a comment | 

5

The file-system directly associates the numerical UID (User ID) and GID (Group ID) values with the file, not the user name and group name (which are strings). So the ls -l command (and any other command that displays the user and group owner of a file) need to get the user and group names from somewhere. The /etc/passwd file is one such source (probably the original and most common source). The manual bears this out - from PASSWD (5) (i.e. the man page for the /etc/passwd file):

many utilities, like ls(1) use it to map user IDs to usernames

share|improve this answer

edited 2 hours ago

answered 2 hours ago

igaligal

5,3711234

add a comment | 

The file-system directly associates the numerical UID (User ID) and GID (Group ID) values with the file, not the user name and group name (which are strings). So the ls -l command (and any other command that displays the user and group owner of a file) need to get the user and group names from somewhere. The /etc/passwd file is one such source (probably the original and most common source). The manual bears this out - from PASSWD (5) (i.e. the man page for the /etc/passwd file):

many utilities, like ls(1) use it to map user IDs to usernames

share|improve this answer

edited 2 hours ago

answered 2 hours ago

igaligal

5,3711234

share|improve this answer

edited 2 hours ago

answered 2 hours ago

igaligal

5,3711234

answered 2 hours ago

igaligal

5,3711234

answered 2 hours ago

igaligal

5,3711234