.\"	$OpenBSD: setproctitle.3,v 1.16 2007/05/31 19:19:28 jmc Exp $
.\"
.\" Copyright (c) 1994, 1995 Christopher G. Demetriou
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.\"    must display the following acknowledgement:
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.\"	 for the NetBSD Project.
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.Dd $Mdocdate: May 31 2007 $
.Dt SETPROCTITLE 3
.Os
.Sh NAME
.Nm setproctitle
.Nd set process title
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Ft void
.Fn setproctitle "const char *fmt" "..."
.Sh DESCRIPTION
The
.Fn setproctitle
function sets the invoking process's title.
The process title is set to the last component of the program
name, followed by a colon, a single space, and the formatted string specified
by
.Fa fmt .
If
.Fa fmt
is
.Dv NULL ,
the colon and formatted string are omitted.
The length of a process title is limited to 2048 bytes.
.Sh EXAMPLES
Set the process title to the program name, with no further information:
.Bd -literal -offset indent
setproctitle(NULL);
.Ed
.Pp
Set the process title to the program name, an informational string,
and the process ID:
.Bd -literal -offset indent
setproctitle("foo! (%d)", getpid());
.Ed
.Sh SEE ALSO
.Xr ps 1 ,
.Xr w 1 ,
.Xr printf 3
.Sh HISTORY
The
.Fn setproctitle
function first appeared in
.Nx 0.9a .
.Sh CAVEATS
It is important never to pass a string with user-supplied data as a
format without using
.Ql %s .
An attacker can put format specifiers in the string to mangle the stack,
leading to a possible security hole.
This holds true even if the string has been built
.Dq by hand
using a function like
.Fn snprintf ,
as the resulting string may still contain user-supplied conversion specifiers
for later interpolation by
.Fn setproctitle .
.Pp
Always be sure to use the proper secure idiom:
.Bd -literal -offset indent
setproctitle("%s", string);
.Ed