Man Exec en anglais
EXEC(P)                    POSIX Programmer's Manual                   EXEC(P)



 

NAME


       exec - execute commands and open, close, or copy file descriptors

 

SYNOPSIS


       exec [command [argument ...]]

 

DESCRIPTION






       The  exec  utility  shall  open, close, and/or copy file descriptors as
       specified by any redirections as part of the command.

       If exec is  specified  without  command  or  arguments,  and  any  file
       descriptors  with  numbers  greater  than  2 are opened with associated
       redirection statements, it is unspecified whether those  file  descrip-
       tors  remain  open when the shell invokes another utility. Scripts con-
       cerned that child shells could misuse open file descriptors can  always
       close them explicitly, as shown in one of the following examples.

       If exec is specified with command, it shall replace the shell with com-
       mand without creating a new process.  If arguments are specified,  they
       shall  be  arguments to command.  Redirection affects the current shell
       execution environment.

 

OPTIONS


       None.

 

OPERANDS


       See the DESCRIPTION.

 

STDIN


       Not used.

 

INPUT FILES


       None.

 

ENVIRONMENT VARIABLES


       None.

 

ASYNCHRONOUS EVENTS


       Default.

 

STDOUT


       Not used.

 

STDERR


       The standard error shall be used only for diagnostic messages.

 

OUTPUT FILES


       None.

 

EXTENDED DESCRIPTION


       None.

 

EXIT STATUS


       If command is specified, exec shall not return to  the  shell;  rather,
       the  exit status of the process shall be the exit status of the program
       implementing command, which overlaid  the  shell.  If  command  is  not
       found, the exit status shall be 127. If command is found, but it is not
       an executable utility, the exit status shall be 126. If  a  redirection
       error  occurs (see Consequences of Shell Errors ), the shell shall exit
       with a value in the range 1-125. Otherwise, exec shall  return  a  zero
       exit status.

 

CONSEQUENCES OF ERRORS


       Default.

       The following sections are informative.

 

APPLICATION USAGE


       None.

 

EXAMPLES


       Open readfile as file descriptor 3 for reading:


              exec 3< readfile

       Open writefile as file descriptor 4 for writing:


              exec 4> writefile

       Make file descriptor 5 a copy of file descriptor 0:


              exec 5<&0

       Close file descriptor 3:


              exec 3<&-

       Cat  the  file maggie by replacing the current shell with the cat util-
       ity:


              exec cat maggie

 

RATIONALE


       Most historical implementations were not conformant in that:


              foo=bar exec cmd

       did not pass foo to cmd.

 

FUTURE DIRECTIONS


       None.

 

SEE ALSO


       Special Built-In Utilities

 

COPYRIGHT


       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                              EXEC(P)