xbian-backup.sh under cron not getting correct DWM value

[jurgenvanimpe]

I was trying to use the build-in functionality to make automatic backups to a USB attached HDD. The script was calling up the script at /etc/cron.daily/xbian-backup.sh It uses the configurations set in the file /etc/default/xbian-snap. Here the variable IMGPLAN should be set to none/daily/weekly/monthly. This I set to daily. But to actually start the backup-up the following if statement has to be true: if [ "$IMGPLAN" = "$DWM" -a "$IMGTYPE" = file ]; then nice -n +1 btrfs-auto-snapshot xbiancopy --img '-' "$IMGDEST" >/dev/null 2>&1 xbian-config xbiancopy doclean "$(xbian-config xbiancopy imgdest)" $IMGKEEP fi IMGPLAN is set to daily but $DWM gives an incrorrect value causing to skip the actual backup commands. The error for me happens in the line: DWM="${0##*.}"; DWM="${DWM%%/*}" The 0 should refer to the full path where the script is, but the statement $(0) is not a reliable way.

My first time trying to help out. Hopefully my explanation helps.

[mkreisl]

@jurgenvanimpe A bit more text would be helpful

There is no "xbian-backup.sh"

Which value would be the right one and which value is set for DWM?

Btw, I can't believe that. Works here for months without any issue on 4 XBian's

[mkreisl]

Hmmm, /etc/{cron.daily,cron.weekly,cron.monthly}/xbian-backup was never the idea to be called by another script, it's invoked by (ana)cron, that's why it is stored there

If you want to call this script from your script, you have to call it with full path name. Then it works

[jurgenvanimpe]

I was trying to get the anacron going but with no luck, so I tried to call the script directly myself for testing purposes. Might be that it works perfectly when called from anacron. But I'm not getting that one to work. I read all your old posts from 2014 about it.

[mkreisl]

cat /etc/cron.daily/xb

#!/bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

. /etc/default/xbian-snap

[ "$ENABLEDSCHEDULE" = yes ] || exit 0

DWM="${0##*.}"; DWM="${DWM%%/*}"

echo "DWM=$DWM"

If I run the testscript manually with full path, it gives me correct output

root@kmxbilr2 ~ # /etc/cron.daily/xb
DWM=daily
root@kmxbilr2 ~ # 

[jurgenvanimpe]

Thanks for the fast reply. I adjusted the file like you did. This is my cat output: sudo head -n 12 /etc/cron.daily/xbian-backup

#!/bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

. /etc/default/xbian-snap

[ "$ENABLEDSCHEDULE" = yes ] || exit 0

DWM="${0##*.}"; DWM="${DWM%%/*}"

echo "DWM=$DWM"

Result of runnin cd /etc/cron.daily && sudo ./xbian-backup: DWM= But strangely when I run: sudo sh /etc/cron.daily/xbian-backup I get: DWM=daily ....Starts running ....

I can't explain this. I didn't study IT or anything and I'm trying to figure it out. Hope you can understand it.

[mkreisl]

I can understand this, but again, it's not an issue. The script requires the full path to figure out from which path (means which cron job is currently running) it has been called

[jurgenvanimpe]

Thanks for clarification. Then this is not an issue. I'll turn my direction to the forum if I have questions on how it exactly works. Because I'm still looking on how to set the timing when it will perform the backup and to get it running properly. Sorry for the inconvience.

[jurgenvanimpe]

Thanks for clarification. Then this is not an issue. I'll turn my direction to the forum if I have questions on how it exactly works. Because I'm still looking on how to set the timing when it will perform the backup and to get it running properly. Sorry for the inconvience.

[mkreisl]

The script is called by anacron per default. If you want to get the time when the jobs are started, please look into file /etc/anacrontab and file /etc/cron.d/anacron In the first one is the delay in minutes configured for the daily, weekly and monthy jobs In the second one is the start time of anacron configured

[mk01]

one can use readlink -f on $0 first like this:

FP="$(readlink -f ${0})"
DWM="${FP##*.}"; DWM="${DWM%%/*}"

[mkreisl]

Hi, @mk01 still alive :smile:

one can use readlink -f on $0 first like this:

FP="$(readlink -f ${0})"
DWM="${FP##*.}"; DWM="${DWM%%/*}"

This does not work if called from another link, for example /etc/cron.monthl/xbian-backup returns daily instead of monthly:

root@kmxbilr2 ~ # cat /etc/cron.daily/xb
#!/bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

. /etc/default/xbian-snap

[ "$ENABLEDSCHEDULE" = yes ] || exit 0

FP="$(readlink -f ${0})"; DWM="${FP##*.}"; DWM="${DWM%%/*}"

echo "DWM=$DWM"
root@kmxbilr2 ~ # ls -la /etc/cron.monthly/xb
lrwxrwxrwx 1 root root 16 Feb 26 14:35 /etc/cron.monthly/xb -> ../cron.daily/xb
root@kmxbilr2 ~ # /etc/cron.monthly/xb
DWM=daily
root@kmxbilr2 ~ #

realpath -s $0 does it however:

root@kmxbilr2 /etc/cron.monthly # cat /etc/cron.daily/xb
#!/bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

. /etc/default/xbian-snap

[ "$ENABLEDSCHEDULE" = yes ] || exit 0

echo $0
FP="$(realpath -s $0)"; DWM="${FP##*.}"; DWM="${DWM%%/*}"

echo "DWM=$DWM"
root@kmxbilr2 /etc/cron.monthly # ls -la xb
lrwxrwxrwx 1 root root 16 Feb 26 14:35 xb -> ../cron.daily/xb
root@kmxbilr2 /etc/cron.monthly # ./xb
./xb
DWM=monthly

[jurgenvanimpe]

Adjusting the files /etc/cron.daily/anacron and /etc/anacrontab works flawless now. I renamed also the script to make sure it starts second in row. I also added a line in the end of the script to trigger rsync to copy the backup off-site. Thanks!

[mkreisl]

@jurgenvanimpe, modifying /etc/cron.daily/xbian-backup script and renaming it is not a good idea, because after next update of the package owning this file (in this case its xbian-package-config-shell), you will have 2 scripts making backups. And, you break links in /etc/cron.weekly and /etc/cron.monthly

[jurgenvanimpe]

@mkreisl The links from cron.monthly/daily were already updated. Getting 2 files that would start making backups is something I didn't forsee. Do you have an elegant suggestion on how to get more control over the timing on execution of xbian-backup without renaming? And the line at the end that I added to perform an rsync, would this be deleted after an update if the xbian-backup gets overwritten? Thought I found a great solution.... appears not to :)

[mkreisl]

@jurgenvanimpe

Do you have an elegant suggestion on how to get more control over the timing on execution of xbian-backup without renaming?

No

You could do this by bypassing the original logic:

1) rename the script (you already did this) 2) ignore ENABLEDSCHEDULE variable in your script (remove this line) 3) set ENABLEDSCHEDULE=no in /etc/default/xbian-snap

Be happy :smile:

And the line at the end that I added to perform an rsync, would this be deleted after an update if the xbian-backup gets overwritten?

If you rename the script, this file is save against updates