I am having problems with getting a crontab
to work. I want to automate a MySQL database backup.
The setup:
From the shell this command works
mysqldump -u user -p[user_password] [database_name] | gzip > dumpfilename.sql.gz
When I place this in a crontab using crontab -e
* * /usr/bin/mysqldump -u user -pupasswd mydatabase | gzip> /home/user/backup/mydatabase-backup-`date +\%m\%d_\%Y`.sql.gz >/dev/null 2>&1
A file is created every minute in /home/user/backup directory, but has 0 bytes.
However when I redirect this output to a second directory, backup2, I note that the proper mysqldumpfile duly compressed is created in it. I am unable to figure what is the mistake that I am making that results in a 0 byte file in the first directory and the expected output in the second directory.
* * /usr/bin/mysqldump -u user -pupasswd my-database | gzip> /home/user/backup/mydatabase-backup-`date +\%m\%d_\%Y`.sql.gz >/home/user/backup2/mydatabase-backup-`date +\%m\%d_\%Y`.sql.gz 2>&1
I would greatly appreciate an explanation.
Thanks
Personally, I have create a file.sh (right 755) in the root directory, file who do this job, on order of the crontab.
Crontab code:
10 2 * * * root /root/backupautomatique.sh
File.sh code:
rm -f /home/mordb-148-251-89-66.sql.gz #(To erase the old one)
mysqldump mor | gzip > /home/mordb-148-251-89-66.sql.gz (what you have done)
scp -P2222 /home/mordb-148-251-89-66.sql.gz root@otherip:/home/mordbexternes/mordb-148-251-89-66.sql.gz
(to send a copy somewhere else if the sending server crashes, because too old, like me ;-))
Besides the solution of m79lkm above, my 2 cents on this topic is not to directly pipe the result in gzip but first dump it as a .sql file, and then gzip it. (Use && instead of | )
The dump itself will be faster. (for what I tested it was double as fast)
Otherwise you tables will be locked longer and the downtime/slow-responding of your application can bother the users. The mysqldump command is taking a lot of resources from your server.
So I would go for "&& gzip" instead of "| gzip"
Important: check for free disk space first with df -h
since you will need more then piping | gzip.
mysqldump -u user -p[user_password] [database_name] > dumpfilename.sql && gzip dumpfilename.sql
-> which will also result in 1 file called dumpfilename.sql.gz
Furthermore the option --single-transaction
prevents the tables being locked but still result in a solid backup. So you might consider to use that option. See docs here
mysqldump --single-transaction -u user -p[user_password] [database_name] > dumpfilename.sql && gzip dumpfilename.sql
You can use the tee
command to redirect output:
/usr/bin/mysqldump -u user -pupasswd my-database | \
tee >(gzip -9 -c > /home/user/backup/mydatabase-backup-`date +\%m\%d_\%Y`.sql.gz) | \
gzip> /home/user/backup2/mydatabase-backup-`date +\%m\%d_\%Y`.sql.gz 2>&1
see documentation here
if you need to add a date-time to your backup file name (Centos7) use the following:
/usr/bin/mysqldump -u USER -pPASSWD DBNAME | gzip > ~/backups/db.$(date +%F.%H%M%S).sql.gz
this will create the file: db.2017-11-17.231537.sql.gz
Source: Stackoverflow.com