EXEC ( 1 ) USER COMMANDSEXEC ( 1 )

NAME

exec - execute command, open/close and duplicate file descriptors

SYNOPSIS

exec [ options ] [command [arg ...]]

DESCRIPTION

exec is a special built-in command that can be used to manipulate file descriptors or to replace the current shell with a new command.

If command is specified, then the current shell process will be replaced by command rather than running command and waiting for it to complete. Note that there is no need to use exec to enhance performance since the shell implicitly uses the exec mechanism internally whenever possible.

If no operands are specified, exec can be used to open or close files, or to manipulate file descriptors from 0 to 9 in the current shell environment using the standard redirection mechanism available with all commands. The close-on-exec flags will be set on file descriptor numbers greater than 2 that are opened this way so that they will be closed when another program is invoked.

Because exec is a special command, any failure will cause the script that invokes it to exit. This can be prevented by invoking exec from the command utility.

exec cannot be invoked from a restricted shell to create files or to open a file for writing or appending.

OPTIONS

-c
Clear all environment variables before executions except variable assignments that are part of the current exec command.
-a name
argv[0] will be set to name for command

EXIT STATUS

If command is specified, exec does not return. Otherwise, the exit status is one of the following:
0
All I/O redirections were successful.
>0
An error occurred.

SEE ALSO

command(1), eval(1)

IMPLEMENTATION

version
exec (AT&T Research) 1999-07-10
author
David Korn <dgk@research.att.com>
copyright
Copyright © 1982-2010 AT&T Intellectual Property
license
http://www.opensource.org/licenses/cpl1.0.txt