We can use Groovy on the command-line to evaluate one-line scripts and pipe output to other commands or use input from other commands. This makes for some command-line scripting. We invoke groovy with the -e argument to evaluate a simple script. We can even use arguments in the script.
Other arguments are -n and -p to process each line of input from a file or from another command. We can also iterate over a list of files, change the contents and use the -i argument to define a backup file pattern when saving the files.
The last argument is -l to start Groovy in listening mode. We can use for example a telnet client to connect to groovy and do some processing.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | // Pipe groovy output to grep.$ groovy -e "Locale.availableLocales.each { println it.displayName }" | grep English// Or do it all in Groovy.$ groovy -e "Locale.availableLocales.displayName.findAll { it =~ args[0] }.each { println it }" English// Using -n and -p to filter each line.$ groovy -e "Locale.availableLocales.each { println it.displayName }" | groovy -ne "if (line =~ 'English') println line"$ groovy -e "Locale.availableLocales.each { println it.displayName }" | groovy -pe "if (line =~ 'English') line"// All will output:EnglishEnglish (United States)English (Malta)English (United Kingdom)English (New Zealand)English (Philippines)English (South Africa)English (Ireland)English (India)English (Australia)English (Canada)English (Singapore) |
Starting Groovy in listening mode:
1 2 3 4 5 6 7 8 | $ groovy -l 9000 -e "println 'You say: ' + line"groovy is listening on port 9000$ telnet localhost 9000Trying 127.0.0.1...Connected to localhost.Escape character is '^]'.Groovy Rocks!You say: Groovy Rocks! |
