How to find out where exactly the packet is being lost

15th June 201616th July 2016 Vladimir Melnik

It’s a pretty common occurrence when you have 2 hosts pinging each other and some packets are being lost. And sometimes you need to make sure, that the routing device […]

IP-address Round-Robin for Postifx

24th September 201516th July 2016 Vladimir Melnik

Here’s a short and pretty self-desctriptive recipe to make your Postfix to send outgoing messages from different IP-addresses switching them on a round-robin basis. First of all, we’ll need the […]

A simple todo list for your shell

2nd March 201516th July 2016 Vladimir Melnik

This simple script lists today’s tasks every time you log in (or create a new window in your screen).

# Just add me to your .bashrc:
# [ -x ~/.bashrc_today ] && . ~/.bashrc_today

TODAYD="${HOME}/.today.d"

if [ ! -d "${TODAYD}/today" ]; then
        mkdir -p "${TODAYD}/today"
fi

TODAY=$(date +%F)

function toDay() {
        local DAY=${1};  shift;
        local CARD=${1}; shift;
        local TODO=${*}
        (
                if [ ! -d "${TODAYD}/${DAY}" ]; then
                        mkdir -p "${TODAYD}/${DAY}"
                fi
        ) && (
                echo "${TODO} [+${TODAY}]" >> "${TODAYD}/${DAY}/${CARD}"
        ) && (
                echo -n "${TODAYD}/${DAY}/${CARD}: "
                cat "${TODAYD}/${DAY}/${CARD}"
        )
}

echo -n -e "Today is \033[0;36m$(date +%A)\033[0m, \033[0;35m${TODAY}\033[0m"

if [ -d "${TODAYD}/${TODAY}" ] && STUFF=$(ls "${TODAYD}/${TODAY}") && [ -n "${STUFF}" ]; then
        for CARD in ${STUFF}; do
                (cat "${TODAYD}/${TODAY}/${CARD}" >> "$TODAYD/today/${CARD}") &&
                        rm -f "${TODAYD}/${TODAY}/${CARD}"
        done
        rmdir "${TODAYD}/${TODAY}"
fi

if [ -d "${TODAYD}/today" ] && STUFF=$(ls -X "${TODAYD}/today/") && [ -n "${STUFF}" ]; then
        echo \ and here\'s what to do:
        for CARD in ${STUFF}; do
                echo -n -e " * \033[1;33m(\033[1;37m${CARD}\033[1;33m)\033[0m "
                cat "${TODAYD}/today/${CARD}"
        done
        echo Good luck!
else
        echo , don\'t you know what to do? =\)
fi

echo

# Just add me to your .bashrc:

# [ -x ~/.bashrc_today ] && . ~/.bashrc_today

TODAYD="${HOME}/.today.d"

if [ ! -d "${TODAYD}/today" ]; then

mkdir -p "${TODAYD}/today"

TODAY=$(date +%F)

function toDay() {

local DAY=${1}; shift;

local CARD=${1}; shift;

local TODO=${*}

(

if [ ! -d "${TODAYD}/${DAY}" ]; then

mkdir -p "${TODAYD}/${DAY}"

) && (

echo "${TODO} [+${TODAY}]" >> "${TODAYD}/${DAY}/${CARD}"

) && (

echo -n "${TODAYD}/${DAY}/${CARD}: "

cat "${TODAYD}/${DAY}/${CARD}"

)

}

echo -n -e "Today is \033[0;36m$(date +%A)\033[0m, \033[0;35m${TODAY}\033[0m"

if [ -d "${TODAYD}/${TODAY}" ] && STUFF=$(ls "${TODAYD}/${TODAY}") && [ -n "${STUFF}" ]; then

for CARD in ${STUFF}; do

(cat "${TODAYD}/${TODAY}/${CARD}" >> "$TODAYD/today/${CARD}") &&

rm -f "${TODAYD}/${TODAY}/${CARD}"

done

rmdir "${TODAYD}/${TODAY}"

if [ -d "${TODAYD}/today" ] && STUFF=$(ls -X "${TODAYD}/today/") && [ -n "${STUFF}" ]; then

echo \ and here\'s what to do:

for CARD in ${STUFF}; do

echo -n -e " * \033[1;33m(\033[1;37m${CARD}\033[1;33m)\033[0m "

cat "${TODAYD}/today/${CARD}"

done

echo Good luck!

else

echo , don\'t you know what to do? =\)

echo

Adding a new task is as easy as typing something […]

Maintenance works without drama: how to inform visitors when the server has been shut down

20th February 201516th July 2016 Vladimir Melnik

Sometimes you need to shut some web-services down for a while to do some maintenance works. Of course, you have warned all users about the scheduled downtime period, but what […]

How to check some host by arping without looking up the corresponding network interface?

14th February 201516th July 2016 Vladimir Melnik

Sometimes you have to check if some host replies on ARP “who-has” requests instead of simply pinging it. You probably need it when the host has its firewall configured to […]

How to restart some service when server’s load average goes high as fuck

13th February 201516th July 2016 Vladimir Melnik

This post’s name and script’s comments are pretty descriptive, right?

#!/bin/bash
#
# Just put it to your crontab:
#
# * * * * * root /root/bin/lalala.sh --la1 50 --la5 20 --laf 10 --service httpd --kill --process httpd
#
# It will kill all httpd processes and restart httpd service when LA1 becomes greater or equal to 50, LA5 - to 20 and LA15 - to 10
#

PATH=/bin:/sbin:/usr/bin

OPTS=$(getopt -n $(basename ${0}) -o 1:5:f:s:kp: -l la1:,la5:,laf:,service:,kill,process: -- "${@}")
if [ "${?}" -ne 0 ]; then
        echo "Can't get options" >&2
        exit 1
fi
eval set -- "${OPTS}"
while :; do
        case "${1}" in
                -1|--la1)
                        THR1="${2}"; shift 2;;
                -5|--la5)
                        THR5="${2}"; shift 2;;
                -f|--laf)
                        THR15="${2}"; shift 2;;
                -s|--service)
                        SERVICE="${2}"; shift 2;;
                -k|--kill)
                        KILL="1"; shift 1;;
                -p|--process)
                        PROCESS="${2}"; shift 2;;
                --)
                        shift; break;;
                *)
                        echo "Can't recognize the option: ${1}"; exit 1;;
        esac
done
if [ -z "${SERVICE}" ]; then
        echo "Can't understand what service shall I restart" >&2
        exit 1
fi
if [ "${KILL}" ] && [ -z "${PROCESS}" ]; then
        echo "Can't understand what process shall I kill" >&2
        exit 1
fi

LA=$(  uptime | sed -r 's/^.*load average: ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?$/\1\t\3\t\5/g' )
LA1=$( echo "${LA}" | cut -f1)
LA5=$( echo "${LA}" | cut -f2)
LA15=$(echo "${LA}" | cut -f3)

if
        [ -n "${THR1}"  ] && [ -n "${LA1}"  ] && [ "${LA1}"  -ge "${THR1}"  ] &&
        [ -n "${THR5}"  ] && [ -n "${LA5}"  ] && [ "${LA5}"  -ge "${THR5}"  ] &&
        [ -n "${THR15}" ] && [ -n "${LA15}" ] && [ "${LA15}" -ge "${THR15}" ];
then
        if [ "${KILL}" ]; then
                while PIDS=$(pidof ${PROCESS}); do
                        echo "Slaying ${PIDS}..."
                        kill -9 ${PIDS}
                        sleep 1
                done
                sleep 10
        else
                service "${SERVICE}" restart
        fi
fi

#!/bin/bash

# Just put it to your crontab:

# * * * * * root /root/bin/lalala.sh --la1 50 --la5 20 --laf 10 --service httpd --kill --process httpd

# It will kill all httpd processes and restart httpd service when LA1 becomes greater or equal to 50, LA5 - to 20 and LA15 - to 10

PATH=/bin:/sbin:/usr/bin

OPTS=$(getopt -n $(basename ${0}) -o 1:5:f:s:kp: -l la1:,la5:,laf:,service:,kill,process: -- "${@}")

if [ "${?}" -ne 0 ]; then

echo "Can't get options" >&2

exit 1

eval set -- "${OPTS}"

while :; do

case "${1}" in

-1|--la1)

THR1="${2}"; shift 2;;

-5|--la5)

THR5="${2}"; shift 2;;

-f|--laf)

THR15="${2}"; shift 2;;

-s|--service)

SERVICE="${2}"; shift 2;;

-k|--kill)

KILL="1"; shift 1;;

-p|--process)

PROCESS="${2}"; shift 2;;

--)

shift; break;;

echo "Can't recognize the option: ${1}"; exit 1;;

esac

done

if [ -z "${SERVICE}" ]; then

echo "Can't understand what service shall I restart" >&2

exit 1

if [ "${KILL}" ] && [ -z "${PROCESS}" ]; then

echo "Can't understand what process shall I kill" >&2

exit 1

LA=$( uptime | sed -r 's/^.*load average: ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?, ([0-9]+)(\.[0-9]+)?$/\1\t\3\t\5/g' )

LA1=$( echo "${LA}" | cut -f1)

LA5=$( echo "${LA}" | cut -f2)

LA15=$(echo "${LA}" | cut -f3)

[ -n "${THR1}" ] && [ -n "${LA1}" ] && [ "${LA1}" -ge "${THR1}" ] &&

[ -n "${THR5}" ] && [ -n "${LA5}" ] && [ "${LA5}" -ge "${THR5}" ] &&

[ -n "${THR15}" ] && [ -n "${LA15}" ] && [ "${LA15}" -ge "${THR15}" ];

then

if [ "${KILL}" ]; then

while PIDS=$(pidof ${PROCESS}); do

echo "Slaying ${PIDS}..."

kill -9 ${PIDS}

sleep 1

done

sleep 10

else

service "${SERVICE}" restart

Of course, you can get all further updates of this script from GitHub: https://gist.github.com/melnik13/04225e4e60a8d66f9ab6. Now you can sleep […]

How to run commands on different servers with different login credentials

13th February 201516th July 2016 Vladimir Melnik

Wouldn’t it be lovely if you could run some command on a bunch of servers? Of course, you can! Most of us would do something like that:

for HOST in host1 host2 host3; do { ssh "${HOST}" "echo ZALOOPA > /var/tmp/zaloopa"; } done

1	for HOST in host1 host2 host3; do { ssh "${HOST}" "echo ZALOOPA > /var/tmp/zaloopa"; } done

But what […]

How to monitor which files are growing faster than other ones?

13th February 201516th July 2016 Vladimir Melnik

If you ever needed a tool to get to know which files are growing faster than other ones, you probably will be quite satisfied with this simple bash-script.

#!/bin/sh

# Checking the spool directory
SPOOL=/var/spool/diskhogs
if [ ! -e "${SPOOL}" ]; then
        mkdir -p "${SPOOL}"
fi
if [ ! -d "${SPOOL}" ]; then
        echo "There are no ${SPOOL} directory" >&2
        exit 1
fi

if [ -z "${1}" ]; then
        DIR=.
else
        DIR="${1}"
fi

FILES=$(find "${DIR}" -type f)

TIME=$(date +%s)
if [ -z "${TIME}" ]; then
        echo "Can't determine current time" >&2
        exit 1
fi

for FILE in ${FILES}; do

        SIZE=$(ls -nl ${FILE} | awk '{ print $5 }')
        if [ -z "${SIZE}" ]; then
                echo "Can't determine size of the ${FILE} file" >&2
                continue
        fi

        sqlite3 "${SPOOL}/db" "INSERT INTO sizes VALUES ('${FILE}', '${TIME}', '${SIZE}');"
        if [ ${?} -ne 0 ]; then
                continue
        fi

done

for PERIOD in 60 300 600 1800 3600 86400; do

        TIME_WAS=$((${TIME} - ${PERIOD}))

        (
                echo "*** Since $(date --date="@${TIME_WAS}") (${PERIOD} seconds ago) ***"
                sqlite3 \
                        "${SPOOL}/db" \
                        "SELECT MAX(size) - MIN(size) AS mm, name
                                FROM sizes
                                WHERE time >= '${TIME_WAS}'
                                GROUP BY name
                                ORDER BY mm
                        ;"
        ) > "${SPOOL}/report_${PERIOD}"

done

#!/bin/sh

# Checking the spool directory

SPOOL=/var/spool/diskhogs

if [ ! -e "${SPOOL}" ]; then

mkdir -p "${SPOOL}"

if [ ! -d "${SPOOL}" ]; then

echo "There are no ${SPOOL} directory" >&2

exit 1

if [ -z "${1}" ]; then

DIR=.

else

DIR="${1}"

FILES=$(find "${DIR}" -type f)

TIME=$(date +%s)

if [ -z "${TIME}" ]; then

echo "Can't determine current time" >&2

exit 1

for FILE in ${FILES}; do

SIZE=$(ls -nl ${FILE} | awk '{ print $5 }')

if [ -z "${SIZE}" ]; then

echo "Can't determine size of the ${FILE} file" >&2

continue

sqlite3 "${SPOOL}/db" "INSERT INTO sizes VALUES ('${FILE}', '${TIME}', '${SIZE}');"

if [ ${?} -ne 0 ]; then

continue

done

for PERIOD in 60 300 600 1800 3600 86400; do

TIME_WAS=$((${TIME} - ${PERIOD}))

(

echo "*** Since $(date --date="@${TIME_WAS}") (${PERIOD} seconds ago) ***"

sqlite3 \

"${SPOOL}/db" \

"SELECT MAX(size) - MIN(size) AS mm, name

FROM sizes

WHERE time >= '${TIME_WAS}'

GROUP BY name

ORDER BY mm

) > "${SPOOL}/report_${PERIOD}"

done

Simply […]

Vladimir Melnik

Just another WordPress website

Linux

How to find out where exactly the packet is being lost

IP-address Round-Robin for Postifx

A simple todo list for your shell

Maintenance works without drama: how to inform visitors when the server has been shut down

How to check some host by arping without looking up the corresponding network interface?

How to restart some service when server’s load average goes high as fuck

How to run commands on different servers with different login credentials

How to monitor which files are growing faster than other ones?

Just another WordPress website

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