---
name: "classad_eval"
section: "1"
platform: "linux"
package: "condor"
version: "23.9.6+dfsg-2.1+b10"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/classad_eval"
---

# classad\_eval(1)

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

## NAME

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.

## SYNOPSIS

**classad\_eval** **-help**

**classad\_eval** \[**-\[ad\]-file** \<*file-name*\>\] \[**-target-file** \<*file-name*\>\] \<*ad* \| *assignment* \| *expression* \| **-quiet**\>+

## DESCRIPTION

**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.

## EXAMPLES

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
```

## EXIT STATUS

Returns 0 on success.

## AUTHOR

Center for High Throughput Computing, University of Wisconsin-Madison

## AUTHOR

HTCondor Team

## COPYRIGHT

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.