classad_eval - Man Page

classad_eval — HTCondor Manual

Evaluate the given ClassAd expression(s) in the context of the given ClassAd attributes, and prints the result in ClassAd format.

classad_eval -help

classad_eval [-[ad]-file <file-name>] [-target-file <file-name>] <ad | assignment | expression | -quiet>+

classad_eval is designed to help you understand and debug ClassAd expressions.  You can supply a ClassAd on the command-line, or via a file, as context for evaluating the expression.  You may also construct a ClassAd one argument at a time, with assignments.

By default, classad_eval will print the ClassAd context used to evaluate the expression before printing the result of the first expression, and for every expression with a new ClassAd thereafter.  You may suppress this behavior with the -quiet flag, which replaces an ad, assignment, or expression, and quiets every expression after it on the command line.

Attributes specified on the command line, including those specified as part of a complete ad, replace attributes in the context ad, which starts empty. You can't remove attributes from the context ad, but you can set them to undefined.

Options, flags, and arguments may be freely intermixed, and take effect in order.

Note that classad_eval uses the new ClassAd syntax: ClassAds specified in a file must be surrounded by square brackets and attribute-value pairs must be separated by semicolons.  For compability with condor_q -long:new and condor_status -long:new, classad_eval will use only the first ClassAd if passed a ClassAd list of them.

Almost every ad, assignment, or expression will require you to single quote them.  There are some exceptions; for instance, the following two commands are equivalent:

$ classad_eval 'a = 2' 'a * 2'
$ classad_eval a=2 a*2

You can specify attributes for the context ad in three ways:

$ classad_eval '[ a = 2; b = 2 ]' 'a + b'
$ classad_eval 'a = 2; b = 2' 'a + b'
$ classad_eval 'a = 2' 'b = 2' 'a + b'

You need not supply an empty ad for expressions that don't reference attributes:

$ classad_eval 'strcat("foo", "bar")'

If you want to evaluate an expression in the context of the job ad, first store the job ad in a file:

$ condor_q -l:new 1227.2 > job.ad
$ classad_eval -quiet -file job.ad 'JobUniverse'

You can extract a machine ad in a similar way:

$ condor_status -l:new slot1@exec-17 > machine.ad
$ classad_eval -quiet -file machine.ad 'Rank'

You may evaluate an expression in order to check a match by using the -target-file option:

$ condor_q -l:new 1227.2 > job.ad
$ condor_status -l:new exec-17 > machine.ad
$ classad_eval -quiet -my-file job.ad -target-ad machine.ad 'MY.requirements' 'TARGET.requirements'

Assignments (including whole ClassAds) are all merged into the context ad:

$ classad_eval 'x = y' 'x' 'y = 7' 'x' '[ x = 6; z = "foo"; ]' 'x'
[ x = y ]
undefined
[ y = 7; x = y ]
7
[ z = "foo"; x = 6; y = 7 ]
6

You can suppress printing the context ad partway through:

$ classad_eval 'x = y' 'x' -quiet 'y = 7' 'x' '[ x = 6; z = "foo"; ]' 'x'
[ x = y ]
undefined
7
6

Returns 0 on success.

Center for High Throughput Computing, University of Wisconsin-Madison

HTCondor Team

1990-2024, Center for High Throughput Computing, Computer Sciences Department, University of Wisconsin-Madison, Madison, WI, US. Licensed under the Apache License, Version 2.0.