pquery is typically used in scripts which invoke other tasks that utilize parameter files. For example, a script may take as input a series of parameter assignments which are then passed to one or more pquery calls within the script to retrieve the values of various parameters. Any (non-hidden) parameters not given a value when invoking the script will then be queried for.
if (`pquery script-name par1 $*` == "yes") then
...
...
endif
In this example, if the user runs the script (named "script-name")
and specifies the value of the "par1" parameter on the command line,
i.e.
% script-name par1=yesthen no query will be generated for the value of "par1".
Behavior of this task depends upon the value of the PFILES environment variable, which is used to specify the location of parameter files. The PFILES variable uses a semicolon delimiter to separate two types of parameter directories:
<user>;<system>
The first path ("user") is one or more "local" (writeable) parameter
directories (typically $HOME/pfiles for a default HEASoft setup),
and the second path ("system") is one or more read-only parameter
directories (typically $HEADAS/syspfiles). When both paths are
equivalent, one may omit the semicolon and duplicate path (for
example, when developing a new task, one might set PFILES="." to
use only the current working directory). Multiple colon-delimited
directories are allowed in both portions of the PFILES variable:
<user1>:<user2>;<system1>:<system2>
The default values from the first "system" path are used the first
time a task is run, or whenever the default values have been updated
more recently than the user's copy of the parameters. The user's
copy is created when a task terminates, and retains any learned
changes to the parameters.
This task will look for a copy of the specified parameter file (or parameter file for the specified task) in the first "user" parameter directory; if the file does not exist there, it will then search all subsequent directories listed in PFILES.
The "-f" flag may be used to disable searching of directories listed in the PFILES variable, allowing instead for specification of a particular parameter file (with a preceding directory path if the file is not in the current working directory).
% pquery ftverify numerrs number of errors (output) [0] 02. Query the numerrs parameter for the task 'ftverify', using the command line to specify the value:
% pquery ftverify numerrs numerrs=0 03. Query the numerrs parameter for the task 'ftverify', disabling the default search of directories listed in PFILES and instead providing the path to a specific parameter file:
% pquery -f /local/data/test/ftverify.par numerrs numerrs=0 0