3.3. EVMS Command Line Interpreter
The EVMS Command Line Interpreter (EVMS CLI) provides a
command-driven user interface for EVMS. The EVMS CLI
helps automate volume management tasks
and provides an interactive mode in situations where the
EVMS GUI is not available.
Because the EVMS CLI is an interpreter, it operates
differently than command line utilities for the
operating system. The options you specify
on the EVMS CLI command line to invoke the EVMS
CLI control how the EVMS CLI operates. For example, the
command line options tell the CLI where to go for commands to
interpret and how
often the EVMS CLI must commit changes to disk.
When invoked, the EVMS CLI prompts for commands.
The volume management commands the EVMS CLI understands
are specified in the /usr/src/evms-1.9.0/engine2/ui/cli/grammar.ps
file that accompanies the EVMS
package. These commands are described in detail in the EVMS
man page, and help on these commands is available from within the EVMS
CLI.
3.3.1. Using the EVMS CLI
Use the evms command to start
the EVMS CLI. If you do not enter an option with
evms, the EVMS CLI starts in
interactive mode. In interactive mode, the EVMS CLI prompts
you for commands. The result of each command is immediately saved
to disk. The EVMS CLI exits when you type exit.
You can modify this behavior by using
the following options with evms:
- -b
This option indicates that you are running in
batch mode and anytime there is a prompt for input from the user,
the default value is accepted automatically. This is the
default behavior with the -f option.
- -c
This option commits changes to disk
only when EVMS CLI exits, not after
each command.
- -f filename
This option tells the EVMS CLI to use
filename as the source of
commands. The EVMS CLI exits when it reaches the
end of
filename.
- -p
This option only parses commands; it does
not execute them.
When combined with the -f option, the
-p option detects syntax errors in
command files.
- -h
This option displays help information
for options used with the evms
command.
- -rl
This option tells the CLI that all remaining items on the
command line are replacement parameters for use with
EVMS commands.
 | NOTE |
|---|
| | Replacement parameters are accessed in EVMS commands using the
$(x) notation, where x is the number identifying which
replacement parameter to use. Replacement parameters are assigned
numbers (starting with 1) as they are encountered on the command line.
Substitutions are not made within comments or quoted strings. An example would be: evms -c -f testcase -rl sda sdb |
sda is the replacement for parameter1 and
sdb is the replacement for parameter2 |
| NOTE |
|---|
| | Information on less commonly used options is available
in the EVMS man page. |
3.3.2. Notes on commands and command files
The EVMS CLI allows multiple commands to be displayed
on a command line. When you specify multiple commands on a
single command line, separate the commands with
a colon ( : ). This is
important for command files because the EVMS CLI sees
a command file as a single long command line. The
EVMS CLI has no concept of lines in the file and
ignores spaces. These features allow a command in
a command file to span several lines and use whatever
indentation or margins that are convenient. The only
requirement is that the command separator (the colon) be present
between commands.
The EVMS CLI ignores spaces unless they
occur within quote marks. Place in quotation marks a name that contains
spaces or other non-printable or control characters. If the name
contains a quotation mark as part of the name, the
quotation mark must be "doubled," as shown in the following
example:
"This is a name containing ""embedded"" quote marks." |
EVMS CLI keywords are not case sensitive, but EVMS
names are case sensitive. Sizes can be input in any units with a unit label, such as KB, MB, GB, or TB.
Finally, C programming language style comments
are supported by the EVMS CLI. Comments can begin and
end anywhere except within a quoted string, as shown in the
following example:
/* This is a comment */
Create:Vo/*This is a silly place for a comment, but it is
allowed.*/lume,"lvm/Sample Container/My LVM
Volume",compatibility |
