substract days with date in bash

[davidtuti]

Hi,

I would like in a shell-script to substract some days with bash, but doesnt works. For do this I do:

david@maquinon:~/tele$ echo $n
3
david@maquinon:~/tele$ diaBusqueda=`date --date='-$n day'`
date: fecha `«-$n day»' inválida

Althought if I do:
david@maquinon:~/tele$ diaBusqueda=`date --date='-3 day'`
It works.

could you help me please?
Many thanks and sorry for my english!

[falconindy]

Use double quotes rather than single quotes to allow the variable to be substituted.


$ n=3
$ date --date "-$n day"
Wed Mar 31 10:14:11 EDT 2010

[JCM_Pico]

Hi, is there any way to make this with a different date format like
$ date +%d

[sisco311]

Yes:


n=3
date --date="-$n days" +'%d'

[fubofo]

Sorry for opening an old post but I would like an answer to similar question.

I have a script that creates daily backups and names them as DAYNAME.tgz

How can I script it so that it keeps only the last 3 days? I have tried below but cannot work it out..


#!/bin/bash

#DELETE ANY OLD BACKUPS IF THEY EXIST
rm -rf /backups/server/full_site/daily/backup_`date -date="-3 day" +'%a'.tgz

tar cvzf /backups/server/full_site/daily/backup_`date +%a`.tgz /home/sites/public_html

Also have a similar setup for months - how can I get it to keep only the last, say 3 months?


#!/bin/bash
tar cvzf /backups/server/full_site/monthly/backup_`date +%d_%m_%y`.tgz /home/sites/public_html

[ofnuts]

Sorry for opening an old post but I would like an answer to similar question.

I have a script that creates daily backups and names them as DAYNAME.tgz

How can I script it so that it keeps only the last 3 days? I have tried below but cannot work it out..


#!/bin/bash

#DELETE ANY OLD BACKUPS IF THEY EXIST
rm -rf /backups/server/full_site/daily/backup_`date -date="-3 day" +'%a'.tgz

tar cvzf /backups/server/full_site/daily/backup_`date +%a`.tgz /home/sites/public_htmlAlso have a similar setup for months - how can I get it to keep only the last, say 3 months?


#!/bin/bash
tar cvzf /backups/server/full_site/monthly/backup_`date +%d_%m_%y`.tgz /home/sites/public_html
If you consider that the last change date of the backup files will normally be the day they have been created, you can use the find command with the appropriate parm (-mtime or -ctime) to list files older than N days.

[apmcd47]

find /backups/server/full_site/monthly -name 'backup_*.tgz' -mtime +90 -print0 | xargs -0 rm -f

should delete files that are 90 days old. If you want something more precise you could look at %j format of date:

$ echo $(( $(date +%j) - $(date --date=-3months +%j) ))
96


Andrew

[fubofo]

Sorry but both of those have me stumped. I'm really noob at shell scripting...and it's late lol