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.\" Copyright (c) 2001 Christopher G. Demetriou
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.\" <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
.\"
.Dd March 29, 2008
.Dt GETPROGNAME 3
.Os
.Sh NAME
.Nm getprogname ,
.Nm setprogname
.Nd get/set the name of the current program
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft const char *
.Fn getprogname "void"
.Ft void
.Fn setprogname "const char *name"
.Sh DESCRIPTION
These utility functions get and set the current program's name
as used by various error-reporting functions.
.Pp
.Fn getprogname
returns the name of the current program.
This function is typically useful when generating error messages
or other diagnostic output.
If the program name has not been set,
.Fn getprogname
will return
.Dv NULL .
.Pp
.Fn setprogname
sets the name of the current program to be the last pathname
component of the
.Fa name
argument.
It should be invoked at the start of the program, using the
.Fa argv[0]
passed into the program's
.Fn main
function.
A pointer into the string pointed to by the
.Fa name
argument is kept as the program name.
Therefore, the string pointed to by
.Fa name
should not be modified during the rest of the program's operation.
.Pp
A program's name can only be set once, and in
.Nx
that is actually
done by program start-up code that is run before
.Fn main
is called.
Therefore, in
.Nx ,
calling
.Fn setprogname
from
.Fn main
has no effect.
However, it does serve to increase the portability of the program:
on other operating systems,
.Fn getprogname
and
.Fn setprogname
may be implemented by a portability library, and a call to
.Fn setprogname
allows that library to know the program name without
modifications to that system's program start-up code.
.Sh SEE ALSO
.Xr err 3 ,
.Xr setproctitle 3
.Sh HISTORY
The
.Nm getprogname
and
.Nm setprogname
function calls appeared in
.Nx 1.6 .
.Sh RESTRICTIONS
The string returned by
.Fn getprogname
is supplied by the invoking process and should not be trusted by
setuid or setgid programs.