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Title: Deploying cron programmaticaly the unix way |
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Author: Solène |
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Date: 31 May 2018 |
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Tags: unix |
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Description: |
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Here is a little script to automatize in some way your crontab |
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deployment when you don't want to use a configuration tool like |
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ansible/salt/puppet etc... This let you package a file in your project |
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containing the crontab content you need, and it will add/update your |
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crontab with that file. |
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The script works this way: |
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$ ./install_cron crontab_solene |
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with *crontab_solene* file being an actual crontab correct, which |
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could looks like this: |
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## TAG ## |
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MAILTO="" |
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*/5 * * * * ( cd ~/dev/reed-alert && ecl --load check.lisp ) |
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*/10 * * * * /usr/local/bin/r2e run |
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1 * * * * vacuumdb -azf -U postgres |
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## END_TAG ## |
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Then it will include the file into my current user crontab, the |
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**TAG** in the file is here to be able to remove it and replace it |
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later with the new version. The script could be easily modified to |
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support the tag name as parameter, if you have multiple deployments |
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using the same user on the same machine. |
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Example: |
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$ crontab -l |
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0 * * * * pgrep iridium | xargs renice -n +20 |
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$ ./install_cron crontab_solene |
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$ crontabl -l |
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0 * * * * pgrep iridium | xargs renice -n +20 |
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## TAG ## |
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MAILTO="" |
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*/5 * * * * ( cd ~/dev/reed-alert && ecl --load check.lisp ) |
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*/10 * * * * /usr/local/bin/r2e run |
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1 * * * * vacuumdb -azf -U postgres |
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## END_TAG ## |
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`0 20 * * * ~/bin/faubackup.sh` I can now reinstall |
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the crontab file. |
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$ crontabl -l |
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0 * * * * pgrep iridium | xargs renice -n +20 |
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## TAG ## |
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MAILTO="" |
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*/5 * * * * ( cd ~/dev/reed-alert && ecl --load check.lisp ) |
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*/10 * * * * /usr/local/bin/r2e run |
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1 * * * * vacuumdb -azf -U postgres |
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## END_TAG ## |
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$ ./install_cron crontab_solene |
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$ crontabl -l |
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0 * * * * pgrep iridium | xargs renice -n +20 |
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## TAG ## |
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MAILTO="" |
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*/5 * * * * ( cd ~/dev/reed-alert && ecl --load check.lisp ) |
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*/10 * * * * /usr/local/bin/r2e run |
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1 * * * * vacuumdb -azf -U postgres |
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0 20 * * * ~/bin/faubackup.sh |
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## END_TAG ## |
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Here is the script: |
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#!/bin/sh |
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echo "Usage: $0 user_crontab_file" |
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exit 1 |
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fi |
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grep "^## TAG ##$" "$1" >/dev/null |
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VALIDATION=$? |
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grep "^## END_TAG ##$" "$1" >/dev/null |
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VALIDATION=$(( VALIDATION + $? )) |
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then |
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echo "file ./${1} needs \"## TAG ##\" and \"## END_TAG ##\" to |
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be used" |
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exit 2 |
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fi |
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awk '{ if($0=="## TAG ##") { hide=1 }; if(hide==0) { print } ; |
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if($0=="## END_TAG ##") { hide=0 }; }' | \ |
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cat - "${1}" | \ |
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crontab - |
