The document discusses various techniques for executing Groovy scripts on Linux and Windows shells. It describes using shebang comments to define Groovy as the interpreter, executing Groovy scripts directly with groovy or through GroovyServ for faster startup times, and parsing command line arguments in Groovy scripts using CliBuilder. It also covers managing dependencies in Groovy scripts with Grape and resolving repositories through configuration files or annotations.

1. Groovy on the shell_
Alexander (Sascha) Klein <alexander.klein@codecentric.de>
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2. Why ?
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3. Groovy is cool
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4. Because I can
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5. To do complex stuff
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6. Testing your scripts
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7. If you know Groovy
better than Bash
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8. About me
Alexander Klein
Branchmanager
codecentric AG
Curiestr. 2
70563 Stuttgart, Germany
+49 (0) 172 529 40 20
alexander.klein@codecentric.de
www.codecentric.de
blog.codecentric.de
@saschaklein
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9. Executing Groovy scripts
$ groovy Test.groovy
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10. She-Bang Comment (#!)
#!/usr/local/bin/groovy
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11. Using the default environment
Defining the classpath
Using system variables
Defining system variables
#!/usr/bin/env groovy
#!/usr/bin/env groovy -cp myjar.jar
#!/usr/bin/env groovy -cp ${HOME}/bin
#!/usr/bin/env VAR1=value1 VAR2=value2 groovy
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12. But
Does not work on Linux
Alternative script for /usr/bin/env
Without defining system variables
#!/bin/bash
ARGS=( $1 ) # separate $1 into multiple space-delimited arguments.
shift # consume $1
PROG=`which ${ARGS[0]}` # find path for executable
unset ARGS[0] # discard executable name
ARGS+=( "$@" ) # remainder of arguments preserved "as-is".
# iterate array and expand variables
declare -a PARAMS
for i in "${ARGS[@]}"
do
PARAMS=("${PARAMS[@]}" "`eval "echo $i"`")
done
exec $PROG "${PARAMS[@]}" # execute the command
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13. 'Hacks' for the rescue
#!/bin/bash
//usr/bin/env /path/to/groovy "$0" $@; exit $?
println "My groovy script"
#!/bin/bash
//usr/bin/true && export CLASSPATH=....
//usr/bin/true && export OPTS="-Dmy.opt1=foo -Dmy.opt2=bar"
//usr/bin/true && export OPTS="$OPTS -Dmy.opt3=foobar"
//path/to/groovy $OPTS "$0" $0; exit $?
println System.env[my.opt1]
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14. 'Hacks' for the rescue
#!/bin/bash
REM=''' '
# bash stuff here
export export CLASSPATH=....
export OPTS="-Dmy.opt1=foo -Dmy.opt2=bar"
export OPTS="$OPTS -Dmy.opt3=foobar"
/path/to/groovy $OPTS "$0" $@
exit $?
' '''
// groovy stuff here
println "My groovy script"
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15. A solution for Windows
@ECHO OFF
REM = /
REM dummy groovy statement in first line with an
REM assignment to a dummy var called REM
SET _JAVA_OPTIONS=
SET CLASSPATH=
C:pathtogroovy "%~dp0%~nx0" %*
GOTO :EOF
/
// dummy groovy annotation to make groovy compiler
// to ignore the first line
@interface ECHO {}
// groovy stuff here
println "My groovy script"
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16. GroovyServ
Faster Startup
JVM process running in the background
Scriptstart ~10-20 times faster
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17. Installation
Windows
GroovyServ is part of the Groovy Windows-Installer
Linux
Mac OS X
Binary package
curl -s "https://get.sdkman.io" | bash
sdk install groovyserv
brew install groovyserv
$ cd /tmp
$ unzip groovyserv-1.1.0-bin.zip
$ groovyserv-1.1.0-bin/bin/setup.sh
export PATH=/tmp/groovyserv-1.1.0/bin:$PATH
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18. Usage
$ groovyclient MyScript.groovy
#!/usr/bin/env groovyclient
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19. Writing Scripts
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20. Restrictions
Classname == Filename
to be found from other script
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21. Executing shell commands
"mkdir foo".execute()
["mkdir", "my directory"].execute()
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22. Workingdir & Environment
"ls".execute([], new File("/tmp"))
"env".execute(["VAR1=Test", "VAR2=Something"], new File("."))
"env".execute([*:System.env, VAR1: 'Test']
.collect{ k,v -> "$k=$v" }, new File("."))
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23. Result access
println "ls".execute().text
println "cmd /c dir".execute().text
"ls".execute().inputStream.eachLine { println it }
"ls".execute().in.eachLine { println it }
"myCommand".execute().err.eachLine { println it }
def proc = new ProcessBuilder("myCommand")
.redirectErrorStream(true).start()
proc.in.eachLine { println it }
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24. Process control
Process process = "mkdir foo".execute()
process.waitFor()
int exitValue = process.exitValue()
if(!exitValue) {
//do your error-handling
}
if(!"mkdir foo".execute().waitFor()) {
//do your error-handling
}
"grep pattern".execute().waitForOrKill(1000)
def process = "myLongRunningCommand".execute()
...
process.destroy()
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25. Process output
Process process = "myCommand".execute()
def out = new StringBuffer()
def err = new StringBuffer()
process.waitForProcessOutput( out, err )
if( out.size() > 0 ) println out
if( err.size() > 0 ) println err
def p = "rm -f foo.tmp".execute([], tmpDir)
p.consumeProcessOutput() // Prevent blocking by small buffer
p.waitFor()
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26. Piping
"less temp.sh".execute().pipeTo("grep Detected".execute()).text
def proc1 = "less temp.sh".execute()
def proc2 = "grep Detected".execute()
proc1 | proc2
println proc2.text
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27. Wildcards
"ls *.java".execute() // won't work
"sh -c ls *.java".execute() // Shell resolves the wildcard
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28. Shell Helper I
class Shell {
final Map env = System.env
File dir = new File('.')
boolean redirectErrorStream = false
long timeout = 5000
Shell env(Map env) {
this.env.putAll(env); return this
}
Shell dir(File dir) {
this.dir = dir; return this
}
Shell dir(String dir) {
this.dir = new File(dir); return this
}
Shell redirectErrorStream(boolean redirectErrorStream = true) {
this.redirectErrorStream = redirectErrorStream; return this
}
Shell timeout(int timeout = 5000) {
this.timeout = timeout; return this
}
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29. Shell Helper II
Process execute(String command) {
new ProcessBuilder(['sh', '-c', command])
.directory(dir)
.redirectErrorStream(redirectErrorStream)
.environment(env.collect{k,v -> "$k=$v"} as String[])
.start()
}
int call(String command, boolean consumeOutput = true) {
Process proc = execute(command)
if(consumeOutput)
proc.consumeProcessOutput()
if(timeout)
proc.waitForOrKill(timeout)
else
proc.waitFor()
return proc.exitValue()
}
def eachLine(String command, Closure action) {
execute(command).in.eachLine(action)
}
}
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30. Shell Helper III
def shell = new Shell()
shell.call("mkdir /tmp/groovy")
shell("echo 123 >> /tmp/groovy/test")
shell.dir("/tmp/groovy").call("echo $HOME >> test2")
shell.eachLine("ls ."){
println "- $it -"
}
shell.eachLine("cat test2"){
println "- $it -"
}
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31. Helpfull stuff
Accessing System-Variables
Accessing System-Properties
Get your PID
println System.env.PWD
println System.properties.'user.dir'
import java.lang.management.*
println ManagementFactory.runtimeMXBean.name.split('@').first()
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32. CliBuilder
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33. Parsing Commandline arguments
DSL ontop of Apache Commons CLI
!#/usr/bin/env groovy
def cli = new CliBuilder(usage: 'MyScript')
cli.with {
v(longOpt: 'version', 'show version information')
}
def opt = cli.parse(args)
if (!opt)
System.exit(2)
if (opt.v) {
println "Version: 1.0.0"
}
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34. A Sample
usage: MyScript [options] [args]
-?,--help usage information
--config <arg> A script for tweaking the configuration
-D <property=value> use value for given property
-s,--source <path> Aliases for '-source'
-source <path> Specify where to find the files
-v,--version version information
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35. The code I
#!/usr/bin/env groovy
def cli = new CliBuilder(usage: 'MyScript [options] [args]')
cli.with {
source(args:1, argName: 'path', optionalArg: false,
'Specify where to find the files')
_ (longOpt: 'config', args:1, argName: 'arg', optionalArg: false,
'A script for tweaking the configuration')
s (longOpt: 'source', args:1, argName:'path', optionalArg: false,
"Aliases for '-source'")
'?' (longOpt: 'help', 'usage information')
v (longOpt: 'version', 'version information')
D (args: 2, valueSeparator: '=', argName: 'property=value',
'use value for given property')
}
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36. The code II
def opt = cli.parse(args)
if (!opt) // usage already displayed by cli.parse()
System.exit(2)
if(opt.'?')
cli.usage()
else if (opt.v)
println "Version: 1.0.0"
else {
if (opt.config)
println "Configuration: $opt.config"
if(opt.D) {
println "Custom properties:"
println opt.Ds.collate(2).collect{ it.join('=') }.join('n')
}
def home = System.properties.'user.dir'
if (opt.s || opt.source)
home = opt.s ?: opt.source
println "Working on files:"
opt.arguments().each println "$home/$it"
}
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37. Questions?
Alexander Klein
Branchmanager
codecentric AG
Curiestr. 2
70563 Stuttgart, Germany
+49 (0) 172 529 40 20
alexander.klein@codecentric.de
www.codecentric.de
blog.codecentric.de
@saschaklein
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38. Dependency
Management
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39. Grape
Groovy Adaptable Packaging Engine
Cachedirectory ~/.groovy/grape
@Grab(group='org.springframework', module='spring-orm',
version='3.2.5.RELEASE')
import org.springframework.jdbc.core.JdbcTemplate
@Grab('org.springframework:spring-orm:3.2.5.RELEASE')
import org.springframework.jdbc.core.JdbcTemplate
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40. @Grab Annotation I
Annotatable everywhere
often seen at import statements
group (String)
Maven groupId or Ivy organization
module (String)
Maven artifactId or Ivy artifact
version (String)
literal
'1.1-RC3'
Ivy range
'[1.0, 2,0]' → 1.0 or 2.0
'[2.1,)' → 2.1 or greater
classifier (String)
'jdk15'
optional
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41. Multiple Dependencies
@Grapes([
@Grab(group='commons-primitives',
module='commons-primitives', version='1.0'),
@Grab(group='org.ccil.cowan.tagsoup',
module='tagsoup', version='0.9.7')
])
class Example {
...
}
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42. Repositories
Configuration in ~/.groovy/grapeConfig.xml
Grape cache → ~/.groovy/grapes
Maven Local → ~/.m2/repository
JCenter (includes Maven Central)
IBiblio
Java.net
http://jcenter.bintray.com
http://www.ibiblio.org
http://download.java.net/maven/2
@GrabResolver(name='restlet', root='http://maven.restlet.org/')
@Grab(group='org.restlet', module='org.restlet', version='1.1.6')
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43. Exclude transitive dependencies
@Grab('net.sourceforge.htmlunit:htmlunit:2.8')
@GrabExclude('xml-apis:xml-apis')
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44. GrabConfig
GrabConfig
systemClassLoader (boolean)
using the System-ClassLoader
initContextClassLoader (boolean)
ContextClassLoader = CL of the current thread
autoDownload (boolean)
automatic downloading
disableChecksums (boolean)
checking checksums
@GrabConfig(systemClassLoader=true)
@Grab(group='mysql', module='mysql-connector-java', version='5.1.6')
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45. Proxy-Configuration
$ groovy -Dhttp.proxyHost=<host> -Dhttp.proxyPort=<port>
-Dhttp.proxyUser=<user> -Dhttp.proxyPassword=<user> yourscript.groovy
JAVA_OPTS = -Dhttp.proxyHost=<host> -Dhttp.proxyPort=<port>
-Dhttp.proxyUser=<user> -Dhttp.proxyPassword=<user>
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