Ensure a TCP/IP interface is available
Note:
If you aren't root, specify the full path: /usr/sbin/if_up.
Syntax:
if_up [-alp] [-m milliseconds] [-r retries] [-s seconds] interface...
Options:
- -a
- Wait until all specified interfaces are configured. The default
is to wait until a single interface is configured.
- -l
- (“el”)
Wait for the network link to be marked as being up.
This causes if_up to wait until the physical network link is up.
This option may not be supported by some drivers.
- -m milliseconds
- Wait this number of milliseconds before rewalking the interface list.
The default is 1000 ms.
- -p
- Wait only until the specified interfaces are present. The default is
to wait until the interfaces are both present and configured. This is useful if you
intend to configure the interface manually, after it's present (e.g., using the
ifconfig
utility).
- -r retries
- The number of times to walk the interface list. The default is 5.
- -s seconds
- Wait this number of seconds before rewalking the interface list.
The default is 1.
- interface
- The name of the interface to wait on (e.g., en0, en1, …).
Description:
You can use this convenience utility while booting
to ensure that a TCP/IP interface is available to those utilities
that require one. It's primarily intended for use with the
dhcp.client.
When if_up is run in the foreground in a
startup script, the script doesn't continue until the
specified interfaces are marked as “UP” and have been assigned
an IP address, or the utility has timed out.
If you specify both the -m and -s options, the
one you specify last prevails.
Files:
- libsocket.so
- The if_up utility requires the libsocket.so shared library.
- /usr/sbin/if_up
- The if_up utility is located in the /usr/sbin/
directory, which isn't included in the default PATH of non-root users.
If you aren't root, specify the full path.
Exit status:
- 0
- Success.
- >0
- An error occurred.