| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
| .\" <mtk.manpages@gmail.com> |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
| .\" Permission is granted to make and distribute verbatim copies of this |
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| .\" |
| .\" Permission is granted to copy and distribute modified versions of this |
| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
| .\" the use of the information contained herein. The author(s) may not |
| .\" have taken the same level of care in the production of this manual, |
| .\" which is licensed free of charge, as they might when working |
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| .\" Formatted or processed versions of this manual, if unaccompanied by |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" |
| .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) |
| .\" Modified 1996-05-27 by Martin Schulze (joey@linux.de) |
| .\" Modified 2003-11-15 by aeb |
| .\" 2008-11-07, mtk, Added an example program for getpwnam_r(). |
| .\" |
| .TH GETPWNAM 3 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| getpwnam, getpwnam_r, getpwuid, getpwuid_r \- get password file entry |
| .SH SYNOPSIS |
| .nf |
| .B #include <sys/types.h> |
| .B #include <pwd.h> |
| .PP |
| .BI "struct passwd *getpwnam(const char *" name ); |
| .BI "struct passwd *getpwuid(uid_t " uid ); |
| .PP |
| .BI "int getpwnam_r(const char *restrict " name \ |
| ", struct passwd *restrict " pwd , |
| .BI " char *restrict " buf ", size_t " buflen , |
| .BI " struct passwd **restrict " result ); |
| .BI "int getpwuid_r(uid_t " uid ", struct passwd *restrict " pwd , |
| .BI " char *restrict " buf ", size_t " buflen , |
| .BI " struct passwd **restrict " result ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR getpwnam_r (), |
| .BR getpwuid_r (): |
| .nf |
| _POSIX_C_SOURCE |
| || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR getpwnam () |
| function returns a pointer to a structure containing |
| the broken-out fields of the record in the password database |
| (e.g., the local password file |
| .IR /etc/passwd , |
| NIS, and LDAP) |
| that matches the username |
| .IR name . |
| .PP |
| The |
| .BR getpwuid () |
| function returns a pointer to a structure containing |
| the broken-out fields of the record in the password database |
| that matches the user ID |
| .IR uid . |
| .PP |
| The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows: |
| .PP |
| .in +4n |
| .EX |
| struct passwd { |
| char *pw_name; /* username */ |
| char *pw_passwd; /* user password */ |
| uid_t pw_uid; /* user ID */ |
| gid_t pw_gid; /* group ID */ |
| char *pw_gecos; /* user information */ |
| char *pw_dir; /* home directory */ |
| char *pw_shell; /* shell program */ |
| }; |
| .EE |
| .in |
| .PP |
| See |
| .BR passwd (5) |
| for more information about these fields. |
| .PP |
| The |
| .BR getpwnam_r () |
| and |
| .BR getpwuid_r () |
| functions obtain the same information as |
| .BR getpwnam () |
| and |
| .BR getpwuid (), |
| but store the retrieved |
| .I passwd |
| structure in the space pointed to by |
| .IR pwd . |
| The string fields pointed to by the members of the |
| .I passwd |
| structure are stored in the buffer |
| .I buf |
| of size |
| .IR buflen . |
| A pointer to the result (in case of success) or NULL (in case no entry |
| was found or an error occurred) is stored in |
| .IR *result . |
| .PP |
| The call |
| .PP |
| sysconf(_SC_GETPW_R_SIZE_MAX) |
| .PP |
| returns either \-1, without changing |
| .IR errno , |
| or an initial suggested size for |
| .IR buf . |
| (If this size is too small, |
| the call fails with |
| .BR ERANGE , |
| in which case the caller can retry with a larger buffer.) |
| .SH RETURN VALUE |
| The |
| .BR getpwnam () |
| and |
| .BR getpwuid () |
| functions return a pointer to a |
| .I passwd |
| structure, or NULL if the matching entry is not found or |
| an error occurs. |
| If an error occurs, |
| .I errno |
| is set to indicate the error. |
| If one wants to check |
| .I errno |
| after the call, it should be set to zero before the call. |
| .PP |
| The return value may point to a static area, and may be overwritten |
| by subsequent calls to |
| .BR getpwent (3), |
| .BR getpwnam (), |
| or |
| .BR getpwuid (). |
| (Do not pass the returned pointer to |
| .BR free (3).) |
| .PP |
| On success, |
| .BR getpwnam_r () |
| and |
| .BR getpwuid_r () |
| return zero, and set |
| .IR *result |
| to |
| .IR pwd . |
| If no matching password record was found, |
| these functions return 0 and store NULL in |
| .IR *result . |
| In case of error, an error number is returned, and NULL is stored in |
| .IR *result . |
| .SH ERRORS |
| .TP |
| .BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ..." |
| The given |
| .I name |
| or |
| .I uid |
| was not found. |
| .TP |
| .B EINTR |
| A signal was caught; see |
| .BR signal (7). |
| .TP |
| .B EIO |
| I/O error. |
| .TP |
| .B EMFILE |
| The per-process limit on the number of open file descriptors has been reached. |
| .TP |
| .B ENFILE |
| The system-wide limit on the total number of open files has been reached. |
| .TP |
| .B ENOMEM |
| .\" not in POSIX |
| Insufficient memory to allocate |
| .I passwd |
| structure. |
| .\" This structure is static, allocated 0 or 1 times. No memory leak. (libc45) |
| .TP |
| .B ERANGE |
| Insufficient buffer space supplied. |
| .SH FILES |
| .TP |
| .I /etc/passwd |
| local password database file |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lb lb lbx |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR getpwnam () |
| T} Thread safety T{ |
| MT-Unsafe race:pwnam locale |
| T} |
| T{ |
| .BR getpwuid () |
| T} Thread safety T{ |
| MT-Unsafe race:pwuid locale |
| T} |
| T{ |
| .BR getpwnam_r (), |
| .BR getpwuid_r () |
| T} Thread safety T{ |
| MT-Safe locale |
| T} |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD. |
| The |
| .I pw_gecos |
| field is not specified in POSIX, but is present on most implementations. |
| .SH NOTES |
| The formulation given above under "RETURN VALUE" is from POSIX.1-2001. |
| It does not call "not found" an error, and hence does not specify what value |
| .I errno |
| might have in this situation. |
| But that makes it impossible to recognize |
| errors. |
| One might argue that according to POSIX |
| .I errno |
| should be left unchanged if an entry is not found. |
| Experiments on various |
| UNIX-like systems show that lots of different values occur in this |
| situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM, and probably others. |
| .\" more precisely: |
| .\" AIX 5.1 - gives ESRCH |
| .\" OSF1 4.0g - gives EWOULDBLOCK |
| .\" libc, glibc up to version 2.6, Irix 6.5 - give ENOENT |
| .\" glibc since version 2.7 - give 0 |
| .\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM |
| .\" SunOS 5.8 - gives EBADF |
| .\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0 |
| .PP |
| The |
| .I pw_dir |
| field contains the name of the initial working directory of the user. |
| Login programs use the value of this field to initialize the |
| .B HOME |
| environment variable for the login shell. |
| An application that wants to determine its user's home directory |
| should inspect the value of |
| .B HOME |
| (rather than the value |
| .IR getpwuid(getuid())\->pw_dir ) |
| since this allows the user to modify their notion of |
| "the home directory" during a login session. |
| To determine the (initial) home directory of another user, |
| it is necessary to use |
| .I getpwnam("username")\->pw_dir |
| or similar. |
| .SH EXAMPLES |
| The program below demonstrates the use of |
| .BR getpwnam_r () |
| to find the full username and user ID for the username |
| supplied as a command-line argument. |
| .PP |
| .EX |
| #include <pwd.h> |
| #include <stdint.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <errno.h> |
| |
| int |
| main(int argc, char *argv[]) |
| { |
| struct passwd pwd; |
| struct passwd *result; |
| char *buf; |
| size_t bufsize; |
| int s; |
| |
| if (argc != 2) { |
| fprintf(stderr, "Usage: %s username\en", argv[0]); |
| exit(EXIT_FAILURE); |
| } |
| |
| bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); |
| if (bufsize == \-1) /* Value was indeterminate */ |
| bufsize = 16384; /* Should be more than enough */ |
| |
| buf = malloc(bufsize); |
| if (buf == NULL) { |
| perror("malloc"); |
| exit(EXIT_FAILURE); |
| } |
| |
| s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result); |
| if (result == NULL) { |
| if (s == 0) |
| printf("Not found\en"); |
| else { |
| errno = s; |
| perror("getpwnam_r"); |
| } |
| exit(EXIT_FAILURE); |
| } |
| |
| printf("Name: %s; UID: %jd\en", pwd.pw_gecos, |
| (intmax_t) pwd.pw_uid); |
| exit(EXIT_SUCCESS); |
| } |
| .EE |
| .SH SEE ALSO |
| .BR endpwent (3), |
| .BR fgetpwent (3), |
| .BR getgrnam (3), |
| .BR getpw (3), |
| .BR getpwent (3), |
| .BR getspnam (3), |
| .BR putpwent (3), |
| .BR setpwent (3), |
| .BR passwd (5) |