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uid.pl -- User and group management on Unix systems
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This module provides and interface to user and group information on Posix systems. In addition, it allows for changing user and group ids. When changing user and group settings for the calling process, bear in mind that:

  • Changing user and groups of the calling process requires permission.
  • The functions setgroups() and initgroups() are not part of the POSIX standard and therefore the derived predicates may not be present.
See also
- Please check the documentation of your OS for details on the semantics of this predicates.
Source getuid(-UID) is det
UID is the real user ID of the calling process.
Source getgid(-GID) is det
GID is the real group ID of the calling process.
Source geteuid(-UID) is det
UID is the effective user ID of the calling process.
Source getegid(-GID) is det
GID is the effective group ID of the calling process.
Source getgroups(-GroupsIDs:list(integer)) is det
GroupsIDs is the set of supplementary group IDs of the calling process. Note that these are numeric identifiers. Use group_info/2 to obtain details on the returned group identifiers.
Source user_info(+User, -UserData) is det
UserData represent the passwd information for User. User is either a numeric UID or a user name. The predicate user_data/3 can be used to extract information from UserData.
Source user_data(?Field, ?UserData, ?Value)
Value is the value for Field in UserData. Defined fields are:
name
Name of the user
password
Password hash of the user (or x if this is not accessible)
uid
Numeric user id of the user
gid
Numeric primary group id of the user
comment
The gecos field
home
Home directory of the user
shell
Default (login) shell of the user.
Source group_info(+Group, -GroupData) is det
GroupData represent the group information for Group. Group is either a numeric GID or a group name. The predicate group_data/3 can be used to extract information from GroupData.
Source group_data(?Field, ?GroupData, ?Value)
Value is the value for Field GroupData. Defined fields are:
name
Name of the user
password
Password hash of the user (or x if this is not accessible)
gid
Numeric group id of the group
members
List of user-names that are member of this group.
Source setuid(+UID)
Set the user id of the calling process.
Source seteuid(+UID)
Set the effective user id of the calling process.
Source setgid(+GID)
Set the group id of the calling process.
Source setegid(+GID)
Set the effective group id of the calling process.
Source initgroups(+User, +Group) is det
Initialise the group access list of the calling process to the registered groups for User and the group Group. This predicate is only available if the underlying OS provides it.
Source setgroups(+Groups:list(integer)) is det
Set the group access list of the caling process to the indicated groups. This predicate is only available if the underlying OS provides it.
Source set_user_and_group(+User) is det
Source set_user_and_group(+User, +Group) is det
Set the UID and GID to the User. User is either a UID or a user name. If Group is not specified, the primary group of User is used. If initgroups/2 is available, the resulting group access list of the calling process consists of the registered groups for User and the specified Group.

Re-exported predicates

The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.

Source set_user_and_group(+User) is det
Source set_user_and_group(+User, +Group) is det
Set the UID and GID to the User. User is either a UID or a user name. If Group is not specified, the primary group of User is used. If initgroups/2 is available, the resulting group access list of the calling process consists of the registered groups for User and the specified Group.