How to find out where exactly the packet is being lost
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 […]
Linux
IP-address Round-Robin for Postifx
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
This simple script lists today’s tasks every time you log in (or create a new window in your screen).
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# 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 |
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
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?
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
This post’s name and script’s comments are pretty descriptive, right? 🙂
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#!/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 |
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
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:
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for HOST in host1 host2 host3; do { ssh "${HOST}" "echo ZALOOPA > /var/tmp/zaloopa"; } done |
But what […]
How to monitor which files are growing faster than other ones?
If you ever needed a tool to get to know which files are growing faster than other ones, you probably will be quite satisfied with this simple bash-script.
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#!/bin/sh # Checking the spool directory SPOOL=/var/spool/diskhogs if [ ! -e "${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 |
Simply […]