snippets

This Project is a collection of my code snippets for personal use, but anyone can share and use it without any permission.

Catalog

1. Shell

1. join: Join elements of an array with a charactor in pure bash.

join ':' a  b c d => a:b:c:d
join '_' 1 2 3 4 => 1_2_3_4

2. split: Split a string into an array using a specied delimiter in pure bash.

split.sh ':' Hello:"Hello    World" => array={"Hello", "Hello    World"}
split ',' 1,2,3,4 => array={1,2,3,4}

3. word count: Word count implemented in pure bash.

./wordCount.sh hello world hello goodbye a a b c a a a
goodbye: 1
a: 5
b: 1
c: 1
hello: 2
world: 1

4. getopts example: getopts usage example.

#while getopts 'u:p:h' OPT # don't supress error, prints an error message and unset OPTARG.
while getopts ':u:p:h' OPT # supress error
do
    case $OPT in
        u)
            echo "parse '-u' option: value=${OPTARG} index=${OPTIND}"
            ;;
        p)
            echo "parse '-p' option: value=${OPTARG} index=${OPTIND}"
            ;;
        h)
            echo "parse '-h' option: value=${OPTARG} index=${OPTIND}"
            ;;
        ?)
            echo "Invalid option at ${OPTIND}"
            ;;
    esac
done

2. C/CPP

3. Golang

4. Python

1. subprocess: Call system command using subprocess module.

def _check_service_name_by_port(port, name):
        p1 = Popen(['lsof', '-i:%s' % port, '-Fc'], stdout=PIPE)
        p2 = Popen(["grep", '-Pic', 'c' + name], stdin=p1.stdout, stdout=PIPE)
        output = p2.communicate()[0]
        return int(output) > 0

2. port scanner: Port scanner in Python.

#!/usr/bin/env python
from socket import *
targetIP = gethostbyname(hostname)
s = socket(AF_INET, SOCK_STREAM)
result = s.connect_ex((targetIP, port))
if(result == 0) :
    print 'Port %d: OPEN' % (i,)
s.close()

3. database query

def query_db(logger, connection_string, query_string):
    try:
        engine = sqlalchemy.create_engine(connection_string)
        res = engine.execute(query_string).first()
    except sqlalchemy.exc.OperationalError as e:
        logger.critical("Operational error '%s'" % e)
    except sqlalchemy.exc.ProgrammingError as e:
        logger.critical("Programming error '%s'" % e)
    else:
        return res[0]

5. Scala

6. Java

7. [Pacemaker]

pcs resource cleanup xxx-server
pcs resource restart xxx-server
pcs resource enable xxx-server