Example: Search Files Using an Op Script
This sample script searches a file on a device
running Junos OS for lines matching a given regular expression. The
example uses the jcs:grep template in an op script.
Requirements
This example uses a device running Junos OS.
Overview and Op Script
The jcs:grep template searches an ASCII file for lines matching a regular expression.
The template resides in the junos.xsl import file, which is included with the standard Junos OS installation
available on all switches, routers, and security devices running Junos
OS. To use the jcs:grep template in a script,
you must import the junos.xsl file
into the script and map the jcs prefix
to the namespace identified by the URI http://xml.juniper.net/junos/commit-scripts/1.0 .
In this example, all values required for the jcs:grep template are defined as global parameters. The values for the parameters
are passed into the script as command-line arguments. The following
script defines two parameters, filename and pattern, which store the values of
the input file path and the regular expression. If you omit either
argument when you execute the script, the script generates an error
and halts execution. Otherwise, the script calls the jcs:grep template and passes in the supplied arguments.
If the regular expression contains a syntax error, the jcs:grep template generates an error: regex error message for each line in the file. If the regular expression syntax
is valid, the template parses the input file. For each match, the
template adds a <match> element, which
contains <input> and <output> child tags, to the result tree. The template writes the matching
string to the <output> child element
and writes the corresponding matching line to the <input> child element:
<match> {
<input>
<output>
}In the SLAX script, the := operator
copies the results of the jcs:grep template
call to a temporary variable and runs the node-set function on that variable. The := operator
ensures that the results variable is a
node-set rather than a result tree fragment so that the script can
access the contents. The XSLT script explicitly calls out the equivalent
steps. The script then loops through all resulting input elements
and prints each match.
XSLT Syntax
<?xml version="1.0" standalone="yes"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:junos="http://xml.juniper.net/junos/*/junos"
xmlns:xnm="http://xml.juniper.net/xnm/1.1/xnm"
xmlns:jcs="http://xml.juniper.net/junos/commit-scripts/1.0" version="1.0">
<xsl:import href="../import/junos.xsl"/>
<xsl:variable name="arguments">
<argument>
<name>filename</name>
<description>name of file in which to search for the specified pattern
</description>
</argument>
<argument>
<name>pattern</name>
<description>regular expression</description>
</argument>
</xsl:variable>
<xsl:param name="filename"/>
<xsl:param name="pattern"/>
<xsl:template match="/">
<op-script-results>
<xsl:choose>
<xsl:when test="$filename = ''">
<xnm:error>
<message>missing mandatory argument 'filename'</message>
</xnm:error>
</xsl:when>
<xsl:when test="$pattern = '';">
<xnm:error>
<message>missing mandatory argument 'pattern'</message>
</xnm:error>
</xsl:when>
<xsl:otherwise>
<xsl:variable name="results-temp">
<xsl:call-template name="jcs:grep">
<xsl:with-param name="filename" select="$filename"/>
<xsl:with-param name="pattern" select="$pattern"/>
</xsl:call-template>
</xsl:variable>
<xsl:variable xmlns:ext="http://xmlsoft.org/XSLT/namespace"
name="results" select="ext:node-set($results-temp)"/>
<output>
<xsl:value-of select="concat('Search for ', $pattern, ' in ', $filename)"/>
</output>
<xsl:for-each select="$results//input">
<output>
<xsl:value-of select="."/>
</output>
</xsl:for-each>
</xsl:otherwise>
</xsl:choose>
</op-script-results>
</xsl:template>
</xsl:stylesheet>
SLAX Syntax
version 1.0;
ns junos = "http://xml.juniper.net/junos/*/junos";
ns xnm = "http://xml.juniper.net/xnm/1.1/xnm";
ns jcs = "http://xml.juniper.net/junos/commit-scripts/1.0";
import "../import/junos.xsl";
var $arguments = {
<argument> {
<name> "filename";
<description> "name of file in which to search for the specified pattern";
}
<argument> {
<name> "pattern";
<description> "regular expression";
}
}
param $filename;
param $pattern;
match / {
<op-script-results> {
if ($filename = '') {
<xnm:error> {
<message> "missing mandatory argument 'filename'";
}
}
else if ($pattern = '') {
<xnm:error> {
<message> "missing mandatory argument 'pattern'";
}
}
else {
var $results := { call jcs:grep($filename, $pattern); }
<output> "Search for " _ $pattern _ " in " _ $filename;
for-each ($results//input) {
<output> .;
}
}
}
}Configuration
Procedure
Step-by-Step Procedure
To download, enable, and run the script:
Copy the XSLT or SLAX script into a text file, name the file grep.xsl or grep.slax as appropriate, and download it to the /var/db/scripts/op/ directory on the device.
In configuration mode, include the
filestatement at the[edit system scripts op]hierarchy level and grep.xsl or grep.slax as appropriate.[edit system scripts op] user@host# set file grep.(slax | xsl)
Issue the
commit and-quitcommand to commit the configuration and to return to operational mode.[edit] user@host# commit and-quit
Execute the op script by issuing the
op grep filename filename pattern patternoperational mode command.
Verification
Verifying the Script Arguments
Purpose
Verify that the argument names and descriptions appear in the command-line interface (CLI) help.
Action
Issue the op grep ? operational mode
command. The CLI lists the possible completions for the script arguments
based on the definitions within the global variable arguments in the script.
user@host> op grep Possible completions: <[Enter]> Execute this command <name> Argument name detail Display detailed output filename name of file in which to search for the specified pattern pattern regular expression | Pipe through a command
Verifying Op Script Execution
Purpose
Verify that the script behaves as expected.
Action
If you issue the op grep command, but you
fail to supply either the filename or the regex pattern, the script
issues an error message and halts execution. For example:
user@host> op grep filename /var/log/messages error: missing mandatory argument 'pattern' user@host> op grep pattern SNMP_TRAP_LINK_DOWN error: missing mandatory argument 'filename'
When you issue the op grep filename filename pattern pattern command, the script lists
all lines from the input file that match the regular expression.
user@host> op grep filename /var/log/messages pattern SNMP_TRAP_LINK_DOWN Search for SNMP_TRAP_LINK_DOWN in /var/log/messages Feb 24 09:04:00 host mib2d[1325]: SNMP_TRAP_LINK_DOWN: ifIndex 543, ifAdminStatus down(2), ifOperStatus down(2), ifName lt-0/1/0.9 Feb 24 09:04:00 host mib2d[1325]: SNMP_TRAP_LINK_DOWN: ifIndex 542, ifAdminStatus down(2), ifOperStatus down(2), ifName lt-0/1/0.10