Janith's questions

I am trying to automate mysql secure installation using linux shell scriping. I have below code got from https://gist.github.com/Mins/4602864.

#!/bin/bash

  MYSQL=$(grep 'temporary password' /var/log/mysqld.log | awk '{print $11}')
  MYSQL_ROOT_PASSWORD="test@123"

  SECURE_MYSQL=$(expect -c "

  set timeout 10
  spawn mysql_secure_installation

  expect "Enter password for user root:"
  send "$MYSQL\r"

  expect "Change the password for root ? ((Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect "New password:"
  send "$MYSQL_ROOT_PASSWORD\r"

  expect "Re-enter new password:"
  send "$MYSQL_ROOT_PASSWORD\r"

  expect "Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect "Remove anonymous users? (Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect "Disallow root login remotely? (Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect "Remove test database and access to it? (Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect "Reload privilege tables now? (Press y|Y for Yes, any other key for No) :"
  send "y\r"

  expect eof
  "))

  echo "$SECURE_MYSQL"

But i am getting error

./sql.sh: command substitution: line 48: syntax error near unexpected token `('
./sql.sh: command substitution: line 48: `      expect "Change the password for root ? ((Press y|Y for Yes, any other key for No) :"'

I have tried to figure out the error but no success.

I have a script to start java application on boot time.

[Unit]
Description=test Background

[Service]
ExecStart=/bin/bash -c "/usr/bin/java -jar /var/www/tset.com/*.jar"
Type=simple
WorkingDirectory=/var/www/test.com

[Install]
WantedBy=multi-user.target

Can we edit this to write pid into a file in specific location?

As an example,

ExecStart=/bin/bash -c "/usr/bin/java -jar /var/www/test.com/*.jar | echo $! > ${RUNNING_PID}"

I have a systemd file to start a jar file. But I want to execute jar file as *.jar. Is there a way to do this?

[Unit]
Description=Test Background

[Service]
ExecStart=/usr/bin/java -jar /var/www/test.com/*.jar
Type=simple
WorkingDirectory=/var/www/test.com

[Install]
WantedBy=multi-user.target

I tried this but not working.

I have a script to start a java application automatically.

# colors
red='\e[0;31m'
green='\e[0;32m'
yellow='\e[0;33m'
reset='\e[0m'

echoRed() { echo -e "${red}$1${reset}"; }
echoGreen() { echo -e "${green}$1${reset}"; }
echoYellow() { echo -e "${yellow}$1${reset}"; }

# Check whether the application is running.
# The check is pretty simple: open a running pid file and check that the process
# is alive.
isrunning() {
  # Check for running app
  if [ -f "$RUNNING_PID" ]; then
    proc=$(cat $RUNNING_PID);
    if /bin/ps --pid $proc 1>&2 >/dev/null;
    then
      return 0
    fi
  fi
  return 1
}

start() {
  if isrunning; then
    echoYellow "Test App Already Running"
    return 0
  fi

  pushd $APPLICATION_DIR > /dev/null
  nohup java -jar *.jar>test.out 2>test.err &
  echo $! > ${RUNNING_PID}
  popd > /dev/null

  if isrunning; then
    echoGreen "Test Application started"
    exit 0
  else
    echoRed "The Test Application has not started - check log"
    exit 3
  fi
}

restart() {
  echo "Restarting Test Application"
  stop
  start
}

stop() {
  echoYellow "Stopping Test Application"
  if isrunning; then
    kill `cat $RUNNING_PID`
    rm $RUNNING_PID
  fi
}

status() {
  if isrunning; then
    echoGreen "Test Application is running"
  else
    echoRed "Test Application is either stopped or inaccessible"
  fi
}

case "$1" in
start)
    start
;;

status)
   status
   exit 0
;;

stop)
    if isrunning; then
        stop
        exit 0
    else
        echoRed "Application not running"
        exit 3
    fi
;;

restart)
    stop
    start
;;

*)
    echo "Usage: $0 {status|start|stop|restart}"
    exit 1
esac

refer:- https://vertx.io/blog/vert-x-3-init-d-script/

when I run this command using sudo service test start, working fine. I want to run this automatically on boot up. I tried to creating test.service file on /etc/systemd/system. When I run services not starting.

[Unit]
Description=Test service
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=test
ExecStart=/etc/init.d/test start

[Install]
WantedBy=multi-user.target

What is wrong with this?

I have a shell script to check port status. After checking the port if it is busy then will kill it.

#check port and kill
checkPort(){
     check=$(sudo netstat -nlpt | grep 2020 | awk '{print $6}')
    word="LISTEN"
    killProcess=$(sudo netstat -nlpt | grep 2020 | awk '{print $7}' |
                  sed 's/.\{5\}$//' | sort -u |  xargs -t kill -9)
    if [[ "$check" == "$word"  ]];
    then
        echo "killing the port 2020"
        $killProcess
     else
        echo "Not Listen"
    fi
}

When I run the $killProcess variable I am getting errors. But if I put the full command as sudo netstat -nlpt | grep 2020 | awk '{print $7}' | sed 's/.\{5\}$//' | sort -u | xargs -t kill -9 inside the if condition, it is working fine. What would be the mistake here?

The errors I get:

kill -9 

Usage:
 kill [options] <pid|name> [...]

Options:
 -a, --all              do not restrict the name-to-pid conversion to processes
                        with the same uid as the present process
 -s, --signal <sig>     send specified signal
 -q, --queue <sig>      use sigqueue(2) rather than kill(2)
 -p, --pid              print pids without signaling them
 -l, --list [=<signal>] list signal names, or convert one to a name
 -L, --table            list signal names and numbers

 -h, --help     display this help and exit
 -V, --version  output version information and exit

I put xargs -i kill -kill {} instead of xargs kill -9. Works fine. Is it a good practice?

I have a command to check the port and kill specific pid running on that port. But I want to modify it to,

1. Check port is busy or available
2. If the port is busy then kill the pid

How can I do this?

Code is given below.

sudo netstat -nlpt | grep 2020 | awk '{print $7}' | sed s+/.*++g | sort -u | xargs -i kill -kill {}

I have an if statement to calculate files and delete all except the latest three files. But I want to run this command remotely. How can I combine ssh with an if condition?

I tried this but no success.

#!/bin/bash

ssh -t  [email protected] "cd /var/www/test.com/backup ;

if [ $(ls  | wc -l) -lt 3  ]
then
    echo "Less"
else [ $(ls -t *.tgz|awk 'NR >3'|xargs rm -f) ]
    echo "deleted"
fi"

The error I got:

ls: cannot access *.tgz: No such file or directory