On Thu, 30 Oct 2003 07:53:35 -0600
Rick Sivernell <[EMAIL PROTECTED]> wrote:
> On Thu, 30 Oct 2003 06:25:39 -0600
> "Vu Pham" <[EMAIL PROTECTED]> wrote:
>
> >
> > ----- Original Message -----
> > From: "James McDonald" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Thursday, October 30, 2003 5:57 AM
> > Subject: Re: username / id
> >
> >
> > > Vu Pham wrote:
> > > > Hi all,
> > > >
> > > > Is there any function to get the user name if uid is known, and vice
> > versa ?
> > > > Similar for group.
> > > >
> > > > Thanks,
> > > >
> > >
> > > cat /etc/passwd | grep ^.*:x:500: | awk -F: '{print $1}'
> > > cat /etc/passwd | grep ^.*:x:[0-9]*:500 | awk -F: '{print $1}'
> > >
> > > This is probably not what you want but it does return a name from uid
> > > or gid...
> >
> > Oh, that works. I would like to know if there is an API so that I can
> > use it in my C app, or do I need to run some commands like your
> > suggestion and capture the output.
> >
> > Thanks, James.
> >
> > Vu
> >
> > _______________________________________________
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> Vu
>
> use exec and put the cat .... in a string. the exec will execute this
> from
> code.
It really is not necessary to program via exec to read a file. Try the
attached code.
Put it in /tmp. Compile with 'make qq', Run as ./qq
--
+����������������������������+�������������������������������+
� Roger Oberholtzer � E-mail: [EMAIL PROTECTED] �
� OPQ Systems AB � WWW: http://www.opq.se/ �
� Erik Dahlbergsgatan 41-43 � Phone: Int + 46 8 314223 �
� 115 34 Stockholm � Mobile: Int + 46 733 621657 �
� Sweden � Fax: Int + 46 8 302602 �
+����������������������������+�������������������������������+
#include <stdio.h>
char *myGetUserName(int target) {
FILE *pwdfile;
static char name[80];
if (!(pwdfile = fopen("/etc/passwd", "r"))) return(0);
while (1) {
char aline[256];
int uid;
if (!fgets(aline, 200, pwdfile)) { name[0] = 0; break; }
sscanf(aline, "%*[^:]:" // login (skip)
"%*[^:]:" // group (skip)
"%d:" // uid
"%*d:" // gid (skip)
"%[^:]", // name
&uid, name);
if (uid == target) break;
}
fclose(pwdfile);
return(name);
}
main ()
{
printf("uid 500 is %s\n", myGetUserName(500));
printf("uid 200 is %s\n", myGetUserName(200));
}
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