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| -rw-r--r-- | man3/getpwnam.3 | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/man3/getpwnam.3 b/man3/getpwnam.3 index 65727c36b5..b0c6354c9a 100644 --- a/man3/getpwnam.3 +++ b/man3/getpwnam.3 @@ -1,4 +1,6 @@ .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) +.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> .\" .\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are @@ -28,6 +30,7 @@ .\" 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 2008-11-07 "GNU" "Linux Programmer's Manual" .SH NAME @@ -232,6 +235,58 @@ To determine the (initial) home directory of another user, it is necessary to use .I getpwnam("username")\->pw_dir or similar. +.SH EXAMPLE +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. + +.nf +#include <pwd.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\\n", 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\\n"); + else { + errno = s; + perror("getpwnam_r"); + } + exit(EXIT_FAILURE); + } + + printf("Name: %s; UID: %ld\n", pwd.pw_gecos, (long) pwd.pw_uid); + exit(EXIT_SUCCESS); +} +.fi .SH "SEE ALSO" .BR endpwent (3), .BR fgetpwent (3), |