[MAN] shutdown

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SHUTDOWN

Section: Linux Programmer's Manual (2)
Updated: 2016-03-15
Index Return to Main Contents

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NAME

shutdown - shut down part of a full-duplex connection  

SYNOPSIS

#include <sys/socket.h>

int shutdown(int sockfd, int how);  

DESCRIPTION

The shutdown() call causes all or part of a full-duplex connection on the socket associated with sockfd to be shut down. If how is SHUT_RD, further receptions will be disallowed. If how is SHUT_WR, further transmissions will be disallowed. If how is SHUT_RDWR, further receptions and transmissions will be disallowed.  

RETURN VALUE

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.  

ERRORS

EBADF

sockfd is not a valid file descriptor.

EINVAL

An invalid value was specified in how (but see BUGS).

ENOTCONN

The specified socket is not connected.

ENOTSOCK

The file descriptor sockfd does not refer to a socket.

 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, 4.4BSD (shutdown() first appeared in 4.2BSD).  

NOTES

The constants SHUT_RD, SHUT_WR, SHUT_RDWR have the value 0, 1, 2, respectively, and are defined in <sys/socket.h> since glibc-2.1.91.  

BUGS

Checks for the validity of how are done in domain-specific code, and before Linux 3.7 not all domains performed these checks. Most notably, UNIX domain sockets simply ignored invalid values. This problem was fixed for UNIX domain sockets in Linux 3.7.  

SEE ALSO

connect(2), socket(2), socket(7)  

COLOPHON

This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

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Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

CONFORMING TO

NOTES

BUGS

SEE ALSO

COLOPHON

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SHUTDOWN

Section: shutdown (8)
Updated:
Index Return to Main Contents

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NAME

shutdown - Halt, power-off or reboot the machine  

SYNOPSIS

shutdown [OPTIONS...] [TIME] [WALL...]

 

DESCRIPTION

shutdown

may be used to halt, power-off or reboot the machine.

The first argument may be a time string (which is usually "now"). Optionally, this may be followed by a wall message to be sent to all logged-in users before going down.

The time string may either be in the format "hh:mm" for hour/minutes specifying the time to execute the shutdown at, specified in 24h clock format. Alternatively it may be in the syntax "+m" referring to the specified number of minutes m from now. "now" is an alias for "+0", i.e. for triggering an immediate shutdown. If no time argument is specified, "+1" is implied.

Note that to specify a wall message you must specify a time argument, too.

If the time argument is used, 5 minutes before the system goes down the /run/nologin file is created to ensure that further logins shall not be allowed.  

OPTIONS

The following options are understood:

--help

Print a short help text and exit.

-H, --halt

Halt the machine.

-P, --poweroff

Power-off the machine (the default).

-r, --reboot

Reboot the machine.

-h

Equivalent to --poweroff, unless --halt is specified.

-k

Do not halt, power-off, reboot, just write wall message.

--no-wall

Do not send wall message before halt, power-off, reboot.

-c

Cancel a pending shutdown. This may be used cancel the effect of an invocation of shutdown with a time argument that is not "+0" or "now".

 

EXIT STATUS

On success, 0 is returned, a non-zero failure code otherwise.  

SEE ALSO

systemd(1), systemctl(1), halt(8), wall(1)

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Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

EXIT STATUS

SEE ALSO

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Time: 04:46:01 GMT, September 16, 2022