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Интерактивная система просмотра системных руководств (man-ов)

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exec (1)
  • exec (1) ( Solaris man: Команды и прикладные программы пользовательского уровня )
  • exec (1) ( FreeBSD man: Команды и прикладные программы пользовательского уровня )
  • exec (1) ( Linux man: Команды и прикладные программы пользовательского уровня )
  • >> exec (1) ( POSIX man: Команды и прикладные программы пользовательского уровня )
  • exec (2) ( Solaris man: Системные вызовы )
  • exec (3) ( FreeBSD man: Библиотечные вызовы )
  • exec (3) ( Русские man: Библиотечные вызовы )
  • exec (3) ( Linux man: Библиотечные вызовы )
  • exec (3) ( POSIX man: Библиотечные вызовы )
  • Ключ exec обнаружен в базе ключевых слов.
  •  

    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 descriptors remain open when the shell invokes another utility. Scripts concerned 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 command 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 utility:

    
    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 .


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    OPTIONS
    OPERANDS
    STDIN
    INPUT FILES
    ENVIRONMENT VARIABLES
    ASYNCHRONOUS EVENTS
    STDOUT
    STDERR
    OUTPUT FILES
    EXTENDED DESCRIPTION
    EXIT STATUS
    CONSEQUENCES OF ERRORS
    APPLICATION USAGE
    EXAMPLES
    RATIONALE
    FUTURE DIRECTIONS
    SEE ALSO
    COPYRIGHT


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