vmcp - send commands to the z/VM control program
] [-b <size>
vmcp allows Linux users to send commands to the control program of z/VM. The
normal usage is to invoke vmcp with the command you want to execute. If the
option is not specified, the whole command line is automatically
translated into uppercase. The response of z/VM is written to the standard
needs a kernel feature represented by the device node /dev/vmcp. The
kernel module defines a buffer size, which limits the length of the response.
Every output larger than the compiled buffer size is silently dropped.
Depending on you shell, please remember to escape special characters like *
using \* instead.
vmcp writes the response to stdout and any error message to stderr. Depending on
the success one of the following return codes is returned:
- No problem in vmcp or CP.
- CP returned a non-zero response code.
Error: non-zero CP response for command '<command>':
is written to stderr. <num> contains the numerical value of the
response code and <command> contains the commands as send to
- The specified buffer was not large enough to hold CP's
response. The command was executed, nevertheless, and the response was
truncated. You can use the --buffer option to increase the response
buffer. The message
Error: output (<num> bytes) was truncated, try --buffer to increase
is written to stderr. <num> contains the necessary buffer size
- Linux reported an error to vmcp. See the error message for
- The options passed to vmcp were erroneous. See the error
messages for details.
To get your user id
vmcp query userid
To attach the device 1234 to your guest
vmcp attach 1234 \*
If add the following line to /etc/sudoers
ALL ALL=NOPASSWD: /sbin/vmcp indicate
every user on the system can run the indicate command
sudo vmcp indicate
The basic idea of vmcp is based on cpint of Neale Fergusson.
- -h or --help
- Print usage information, then exit
- -v or --version
- Print version information, then exit
- -k or --keepcase
- Using this option, vmcp does not convert the command to
uppercase. (The default is to translate the command string to uppercase)
- -b <size> or --buffer=<size>
- Specify a buffer size for the response. The buffer size can
be specified from 4096 bytes (4k) to 1048576 Bytes (1M). The default size
is 2 pages (8192 Bytes). You can also use k/K/m/M for kilobytes and