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Articles taggués ‘crontab’

Cron Job Tutorial: Crontab Scheduling Syntax and Script Example

23/10/2018 Comments off

source: Devshed

Crontabs is very useful when doing website maintenance. You can use this feature for the following purposes:

  1. Deleting all files in a certain folder at regular intervals. If you accept user-uploaded files, then eventually it will clog your web hosting server. If you do not regularly delete these files, they will consume a lot of disk space and can slow down your website.
  2. Deleting files of a specific type at regular intervals. You can also choose to delete files of a specific type, instead of deleting all of the files in the folder. If you have PHP, HTML and MP3 files together inside the folder, you can delete only the MP3 files.
  3. Regularly backing up your MySQL database. This is one of the most important webmaster tasks. By using crontabs or the cron job feature, you can create a PHP script that will back up a selected MySQL database, and have it execute automatically executed at a specific, regular interval (e.g monthly, yearly, etc).

This tutorial will focus on creating a cron PHP script application, then configuring your cron hosting feature to execute these scripts automatically. Lire la suite…

Categories: Système Tags: , , ,

How to list the crontabs for all users?

02/10/2018 Comments off

I ended up writing a script (I’m trying to teach myself the finer points of bash scripting, so that’s why you don’t see something like Perl here). It’s not exactly a simple affair, but it does most of what I need. It uses Kyle’s suggestion for looking up individual users’ crontabs, but also deals with /etc/crontab(including the scripts launched by run-parts in /etc/cron.hourly/etc/cron.daily, etc.) and the jobs in the /etc/cron.d directory.source: How do I list all cron jobs for all users?

I ended up writing a script (I’m trying to teach myself the finer points of bash scripting, so that’s why you don’t see something like Perl here). It’s not exactly a simple affair, but it does most of what I need. It uses Kyle’s suggestion for looking up individual users’ crontabs, but also deals with /etc/crontab(including the scripts launched by run-parts in /etc/cron.hourly/etc/cron.daily, etc.) and the jobs in the /etc/cron.d directory.

It takes all of those and merges them into a display something like the following:

#!/bin/bash
# System-wide crontab file and cron job directory. Change these for your system.
 CRONTAB='/etc/crontab'
 CRONDIR='/etc/cron.d'
# Single tab character. Annoyingly necessary.
 tab=$(echo -en "\t")
# Given a stream of crontab lines, exclude non-cron job lines, replace
 # whitespace characters with a single space, and remove any spaces from the
 # beginning of each line.
 function clean_cron_lines() {
 while read line ; do
 echo "${line}" |
 egrep --invert-match '^($|\s*#|\s*[[:alnum:]_]+=)' |
 sed --regexp-extended "s/\s+/ /g" |
 sed --regexp-extended "s/^ //"
 done;
 }
# Given a stream of cleaned crontab lines, echo any that don't include the
 # run-parts command, and for those that do, show each job file in the run-parts
 # directory as if it were scheduled explicitly.
 function lookup_run_parts() {
 while read line ; do
 match=$(echo "${line}" | egrep -o 'run-parts (-{1,2}\S+ )*\S+')
if [[ -z "${match}" ]] ; then
 echo "${line}"
 else
 cron_fields=$(echo "${line}" | cut -f1-6 -d' ')
 cron_job_dir=$(echo "${match}" | awk '{print $NF}')
if [[ -d "${cron_job_dir}" ]] ; then
 for cron_job_file in "${cron_job_dir}"/* ; do # */
 [[ -f "${cron_job_file}" ]] && echo "${cron_fields} ${cron_job_file}"
 done
 fi
 fi
 done;
 }
# Temporary file for crontab lines.
 temp=$(mktemp) || exit 1
# Add all of the jobs from the system-wide crontab file.
 cat "${CRONTAB}" | clean_cron_lines | lookup_run_parts >"${temp}"
# Add all of the jobs from the system-wide cron directory.
 cat "${CRONDIR}"/* | clean_cron_lines >>"${temp}" # */
# Add each user's crontab (if it exists). Insert the user's name between the
 # five time fields and the command.
 while read user ; do
 crontab -l -u "${user}" 2>/dev/null |
 clean_cron_lines |
 sed --regexp-extended "s/^((\S+ +){5})(.+)$/\1${user} \3/" >>"${temp}"
done <
# Output the collected crontab lines. Replace the single spaces between the
 # fields with tab characters, sort the lines by hour and minute, insert the
 # header line, and format the results as a table.
 cat "${temp}" |
 sed --regexp-extended "s/^(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(.*)$/\1\t\2\t\3\t\4\t\5\t\6\t\7/" |
 sort --numeric-sort --field-separator="${tab}" --key=2,1 |
 sed "1i\mi\th\td\tm\tw\tuser\tcommand" |
 column -s"${tab}" -t
rm --force "${temp}"

source: How do I list all cron jobs for all users?

Change & Set the Default crontab Editor

01/10/2018 Comments off


Most hardcore command line users and unix geeks love vi, but I prefer nano. If you want to change your default crontab editor to nano, here’s how to do this:

For a one time edit, launch the terminal and type:

EDITOR=nano crontab -e

If you want to set nano as your default editor in general, you use this command:

export EDITOR=nano

Now when you go to edit crontab, nano will be the default editor than vi. You can test this by typing:

crontab -e

Looking beyond Mac OS X, this should work in Linux as well.

Categories: Système Tags: , , , ,

Scripts shell de sauvegarde

21/06/2017 Comments off

Une des façons les plus simples de sauvegarder un système utilise un script shell. Par exemple, un script peut être utilisé pour configurer les répertoires à sauvegarder et transmettre ces répertoires comme arguments à l’utilitaire tar, ce qui crée un fichier d’archive. Le fichier d’archive peut ensuite être déplacé ou copié dans un autre emplacement. L’archive peut également être créée sur un système de fichiers distant tel qu’un montage NFS.

L’utilitaire tar crée un fichier d’archive de plusieurs fichiers ou répertoires. tar peut également filtrer les fichiers par le biais des utilitaires de compression, réduisant ainsi la taille du fichier d’archive.

Categories: Système Tags: , , ,

Dumper une base MySQL avec horodatage dans le nom du fichier

03/04/2017 Comments off

J’ai un projet qui utilise la base de données MySQL. Je souhaite sauvegarder la base de données tous les jours, donc j’utilise ceci:

mysqldump -h host -u user -p database de mots de passe> 'location.sql'

Je souhaite que les fichiers soient nommés avec l’horodatage, c’est-à-dire:

Aujourd’hui, le fichier sera nommé quelque chose-07-05-2014 08-00-00
Demain sera quelque chose-08-05-2014 08-00-00

Comment ajouter un timestamp formaté avec le nom de fichier exporté?

Réponse:

Une solution serait:

mysqldump -h host -u user -p password database > quelque chose-$(date +%d-%m-%Y %H %M %S).sql

Pour un horodatée qui permette le tri correct des fichiers, il fait changer l’ordre des paramètres et utiliser:

%Y-%m-%d

de manière à trier sur année, mois puis jour. Ne rien changer pour les hh:mm:ss puisque le tri se fair naturellement dans cas.

Pour automatiser ce dump, il faut insérer cette commande dans le crontab (du root ou de l’utilisateur):

0 */8 * * * root /usr/bin/mysqldump -h host -u user -p password database > quelque chose-$(date +%d-%m-%Y %H %M %S).sql

pour que la commande s’exécute toutes les 3 heures (24h ÷ 8).

Categories: Système Tags: , , ,