The document provides a comprehensive guide on using Groovy for shell scripting, detailing script execution methods, environment management, and process control. It includes examples of writing scripts, accessing system variables, and executing shell commands, along with tips for dependency management using Grape. The author, Alexander Klein, emphasizes Groovy's advantages in handling complex scripting tasks compared to traditional methods.

1. GROOVYON
THESHELL
SHELLSCRIPTINGWITHGROOVY
Alexander Klein /http://codecentric.de alexander.klein@codecentric.de
0

2. WHY?

3. GROOVY
IS
COOL

4. BECAUSE
I
CAN

5. TODOCOMPLEXSTUFF

6. TESTINGYOURSCRIPTS

7. IFYOUKNOWGROOVY
BETTERTHANBASH

8. ALEXANDER(SASCHA)KLEIN
Principal Consultant
codecentric AG
Stuttgart
Groovy, JavaFX, UI / UX
Griffon committer
alexander.klein@codecentric.de
@saschaklein
http://gplus.to/karfunkel

9. EXECUTING
GROOVY
SCRIPTS$ groovy Test.groovy

10. SHE-BANG-COMMENT(#!)
#!/usr/local/bin/groovy

11. USINGTHEDEFAULT
ENVIRONMENT
#!/usr/bin/env groovy
DEFININGTHECLASSPATH
#!/usr/bin/env groovy -cp myjar.jar
USINGSYSTEMVARIABLES
#!/usr/bin/env groovy -cp ${HOME}/bin
DEFININGSYSTEMVARIABLES
#!/usr/bin/env VAR1=value1 VAR2=value2 groovy

12. BUT
DOESNOTWORKONLINUX
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

13. GROOVYSERV

14. FASTERSTARTUP
JVM process running in the background
Scriptstart ~10-20 times faster

15. INSTALLATION
WINDOWS
GroovyServ is part of the Groovy Windows-Installer
LINUX
gvm install groovyserv
MACOSX
brew install groovyserv
BINARYPACKAGE
$ cd /tmp
$ unzip groovyserv-1.0.0-bin.zip
$ groovyserv-1.0.0-bin/bin/setup.sh
export PATH=/tmp/groovyserv-1.0.0/bin:$PATH

16. USAGE
groovyclient MyScript.groovy
#!/usr/bin/env groovyclient

17. WRITING
SCRIPTS

18. RESTRICTIONS
Classname == Filename
to be found from other script

19. EXECUTING
SHELLCOMMANDS
"mkdir foo".execute()
["mkdir", "my directory"].execute()

20. 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("."))

21. RESULTACCESS
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 }

22. PROCESSCONTROL
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()

23. PROCESSOUTPUT
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()

24. 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

25. WILDCARDS
"ls *.java".execute() // won't work
"sh -c ls *.java".execute() // Shell resolves the wildcard

26. SHELLHELPERI
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
}

27. SHELLHELPERII
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)
}
}

28. SHELLHELPERIII
def shell = new Shell()
shell.call("mkdir /tmp/groovy")
shell.call("echo 123 >> /tmp/groovy/test")
shell.dir("/tmp/groovy").call("echo $HOME >> test2")
shell.eachLine("ls ."){
println "- $it -"
}
shell.eachLine("cat test2"){
println "- $it -"
}

29. HELPFULLSTUFF
ACCESSINGSYSTEM-VARIABLES
println System.env.PWD
ACCESSINGSYSTEM-PROPERTIES
println System.properties.'user.dir'
GETYOURPID
import java.lang.management.*
println ManagementFactory.runtimeMXBean.name.split('@').first().toInteger()

30. CLIBUILDER

31. PARSINGCOMMANDLINE
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"
}

32. ASAMPLE
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

33. THECODEI
#!/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')
}

34. THECODEII
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"
}

35. DEPENDENCY
MANAGEMENT

36. GRAPE
GROOVYADAPTABLEPACKAGINGENGINE
@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
Cachedirectory ~/.groovy/grape

37. @GRABANNOTATIONI
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

38. MULTIPLEDEPENDENCIES
@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 {
...
}

39. REPOSITORIES
Configuration in ~/.groovy/grapeConfig.xml
Grape cache -> ~/.groovy/grapes
Maven Local -> ~/.m2/repository
JCenter (includes Maven Central)
Codehaus.org
IBiblio
Java.net
http://jcenter.bintray.com
http://repository.codehaus.org
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')

40. EXCLUDETRANSITIVEDEPENDENCIES
@Grab('net.sourceforge.htmlunit:htmlunit:2.8')
@GrabExclude('xml-apis:xml-apis')

41. GRABCONFIG
@GrabConfig(systemClassLoader=true)
@Grab(group='mysql', module='mysql-connector-java', version='5.1.6')
GrabConfig
systemClassLoader (boolean)
using the System-ClassLoader
initContextClassLoader (boolean)
ContextClassLoader = CL of the current thread
autoDownload (boolean)
automatic downloading
disableChecksums (boolean)
checking checksums

42. 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>

43. QUESTIONS?
Alexander (Sascha) Klein
codecentric AG
Curiestr. 2
70563 Stuttgart
tel +49.711.67400-328
mobile +49.172.5294020
alexander.klein@codecentric.de
@saschaklein
http://www.codecentric.de
http://blog.codecentric.de