Cron runs only once instead every minute
16
I'm trying to run a script every minute (on a Docker container running Ubuntu 16.04).
The /etc/echo.sh simply echo the word "hi"
cat /etc/crontab
* * * * * root /etc/echo.sh > /var/log/cron.log 2>&1
/etc/init.d/cron reload
* Reloading configuration files for periodic command scheduler cron [ OK ]
tail -f /var/log/cron.log
hi
After printing "hi" once, nothing happens anymore.
Any ideas why?
linux ubuntu cron crontab
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
add a comment |
16
I'm trying to run a script every minute (on a Docker container running Ubuntu 16.04).
The /etc/echo.sh simply echo the word "hi"
cat /etc/crontab
* * * * * root /etc/echo.sh > /var/log/cron.log 2>&1
/etc/init.d/cron reload
* Reloading configuration files for periodic command scheduler cron [ OK ]
tail -f /var/log/cron.log
hi
After printing "hi" once, nothing happens anymore.
Any ideas why?
linux ubuntu cron crontab
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
8
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
4
Look at the cron.log's time stamp withls -l var/log/cron.log. Notice anything?
– Jens
Feb 9 at 11:34
add a comment |
16
16
16
2
I'm trying to run a script every minute (on a Docker container running Ubuntu 16.04).
The /etc/echo.sh simply echo the word "hi"
cat /etc/crontab
* * * * * root /etc/echo.sh > /var/log/cron.log 2>&1
/etc/init.d/cron reload
* Reloading configuration files for periodic command scheduler cron [ OK ]
tail -f /var/log/cron.log
hi
After printing "hi" once, nothing happens anymore.
Any ideas why?
linux ubuntu cron crontab
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
I'm trying to run a script every minute (on a Docker container running Ubuntu 16.04).
The /etc/echo.sh simply echo the word "hi"
cat /etc/crontab
* * * * * root /etc/echo.sh > /var/log/cron.log 2>&1
/etc/init.d/cron reload
* Reloading configuration files for periodic command scheduler cron [ OK ]
tail -f /var/log/cron.log
hi
After printing "hi" once, nothing happens anymore.
Any ideas why?
linux ubuntu cron crontab
linux ubuntu cron crontab
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
edited Feb 10 at 15:01
Kamil Maciorowski
28.8k156287
28.8k156287
asked Feb 8 at 16:58
SigSig
246211
asked Feb 8 at 16:58
SigSig
246211
asked Feb 8 at 16:58
SigSig
246211
246211
8
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
4
Look at the cron.log's time stamp withls -l var/log/cron.log. Notice anything?
– Jens
Feb 9 at 11:34
add a comment |
8
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
4
Look at the cron.log's time stamp withls -l var/log/cron.log. Notice anything?
– Jens
Feb 9 at 11:34
8
8
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
4
4
Look at the cron.log's time stamp with
ls -l var/log/cron.log. Notice anything?– Jens
Feb 9 at 11:34
Look at the cron.log's time stamp with
ls -l var/log/cron.log. Notice anything?– Jens
Feb 9 at 11:34
add a comment |
1 Answer
1
active
oldest
votes
55
The script does run every minute but > truncates the file each time.
If the file does not exist, it shall be created; otherwise, it shall be truncated to be an empty file after being opened.
(source)
Use >> instead to append to the file.
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
Won'ttailsaytail: cron.log: file truncatedif the file is truncated? Or am I misunderstanding how tail works
– Ferrybig
Feb 8 at 20:27
3
@Ferrybig Iftailnotices the short moment between truncating and placinghiback, then it will. In my Kubuntuecho hi > cron.logtriggers the message fromtailin about half the cases. It's a race condition so your (and the OP's) mileage may vary.
– Kamil Maciorowski
Feb 8 at 20:54
23
And this is why you always usedateinstead ofecho hiwhen testing something like this.
– marcelm
Feb 9 at 2:07
3
@jpmc26 Whatdateis that? The standard Unixdateprints the date and time by default.
– Barmar
Feb 9 at 6:52
3
@Barmar Actually, I've checked and apparently I was confused by the use of-I. Apologies.
– jpmc26
Feb 9 at 6:56
|
show 2 more comments
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1 Answer
1
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oldest
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1 Answer
1
active
oldest
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active
oldest
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active
oldest
votes
55
The script does run every minute but > truncates the file each time.
If the file does not exist, it shall be created; otherwise, it shall be truncated to be an empty file after being opened.
(source)
Use >> instead to append to the file.
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
Won'ttailsaytail: cron.log: file truncatedif the file is truncated? Or am I misunderstanding how tail works
– Ferrybig
Feb 8 at 20:27
3
@Ferrybig Iftailnotices the short moment between truncating and placinghiback, then it will. In my Kubuntuecho hi > cron.logtriggers the message fromtailin about half the cases. It's a race condition so your (and the OP's) mileage may vary.
– Kamil Maciorowski
Feb 8 at 20:54
23
And this is why you always usedateinstead ofecho hiwhen testing something like this.
– marcelm
Feb 9 at 2:07
3
@jpmc26 Whatdateis that? The standard Unixdateprints the date and time by default.
– Barmar
Feb 9 at 6:52
3
@Barmar Actually, I've checked and apparently I was confused by the use of-I. Apologies.
– jpmc26
Feb 9 at 6:56
|
show 2 more comments
55
The script does run every minute but > truncates the file each time.
If the file does not exist, it shall be created; otherwise, it shall be truncated to be an empty file after being opened.
(source)
Use >> instead to append to the file.
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
Won'ttailsaytail: cron.log: file truncatedif the file is truncated? Or am I misunderstanding how tail works
– Ferrybig
Feb 8 at 20:27
3
@Ferrybig Iftailnotices the short moment between truncating and placinghiback, then it will. In my Kubuntuecho hi > cron.logtriggers the message fromtailin about half the cases. It's a race condition so your (and the OP's) mileage may vary.
– Kamil Maciorowski
Feb 8 at 20:54
23
And this is why you always usedateinstead ofecho hiwhen testing something like this.
– marcelm
Feb 9 at 2:07
3
@jpmc26 Whatdateis that? The standard Unixdateprints the date and time by default.
– Barmar
Feb 9 at 6:52
3
@Barmar Actually, I've checked and apparently I was confused by the use of-I. Apologies.
– jpmc26
Feb 9 at 6:56
|
show 2 more comments
55
55
55
The script does run every minute but > truncates the file each time.
If the file does not exist, it shall be created; otherwise, it shall be truncated to be an empty file after being opened.
(source)
Use >> instead to append to the file.
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
The script does run every minute but > truncates the file each time.
If the file does not exist, it shall be created; otherwise, it shall be truncated to be an empty file after being opened.
(source)
Use >> instead to append to the file.
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
edited Feb 8 at 19:34
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
answered Feb 8 at 17:11
Kamil MaciorowskiKamil Maciorowski
28.8k156287
28.8k156287
Won'ttailsaytail: cron.log: file truncatedif the file is truncated? Or am I misunderstanding how tail works
– Ferrybig
Feb 8 at 20:27
3
@Ferrybig Iftailnotices the short moment between truncating and placinghiback, then it will. In my Kubuntuecho hi > cron.logtriggers the message fromtailin about half the cases. It's a race condition so your (and the OP's) mileage may vary.
– Kamil Maciorowski
Feb 8 at 20:54
23
And this is why you always usedateinstead ofecho hiwhen testing something like this.
– marcelm
Feb 9 at 2:07
3
@jpmc26 Whatdateis that? The standard Unixdateprints the date and time by default.
– Barmar
Feb 9 at 6:52
3
@Barmar Actually, I've checked and apparently I was confused by the use of-I. Apologies.
– jpmc26
Feb 9 at 6:56
|
show 2 more comments
Won'ttailsaytail: cron.log: file truncatedif the file is truncated? Or am I misunderstanding how tail works
– Ferrybig
Feb 8 at 20:27
3
@Ferrybig Iftailnotices the short moment between truncating and placinghiback, then it will. In my Kubuntuecho hi > cron.logtriggers the message fromtailin about half the cases. It's a race condition so your (and the OP's) mileage may vary.
– Kamil Maciorowski
Feb 8 at 20:54
23
And this is why you always usedateinstead ofecho hiwhen testing something like this.
– marcelm
Feb 9 at 2:07
3
@jpmc26 Whatdateis that? The standard Unixdateprints the date and time by default.
– Barmar
Feb 9 at 6:52
3
@Barmar Actually, I've checked and apparently I was confused by the use of-I. Apologies.
– jpmc26
Feb 9 at 6:56
Won't
tail say tail: cron.log: file truncated if the file is truncated? Or am I misunderstanding how tail works– Ferrybig
Feb 8 at 20:27
Won't
tail say tail: cron.log: file truncated if the file is truncated? Or am I misunderstanding how tail works– Ferrybig
Feb 8 at 20:27
3
3
@Ferrybig If
tail notices the short moment between truncating and placing hi back, then it will. In my Kubuntu echo hi > cron.log triggers the message from tail in about half the cases. It's a race condition so your (and the OP's) mileage may vary.– Kamil Maciorowski
Feb 8 at 20:54
@Ferrybig If
tail notices the short moment between truncating and placing hi back, then it will. In my Kubuntu echo hi > cron.log triggers the message from tail in about half the cases. It's a race condition so your (and the OP's) mileage may vary.– Kamil Maciorowski
Feb 8 at 20:54
23
23
And this is why you always use
date instead of echo hi when testing something like this.– marcelm
Feb 9 at 2:07
And this is why you always use
date instead of echo hi when testing something like this.– marcelm
Feb 9 at 2:07
3
3
@jpmc26 What
date is that? The standard Unix date prints the date and time by default.– Barmar
Feb 9 at 6:52
@jpmc26 What
date is that? The standard Unix date prints the date and time by default.– Barmar
Feb 9 at 6:52
3
3
@Barmar Actually, I've checked and apparently I was confused by the use of
-I. Apologies.– jpmc26
Feb 9 at 6:56
@Barmar Actually, I've checked and apparently I was confused by the use of
-I. Apologies.– jpmc26
Feb 9 at 6:56
|
show 2 more comments
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8
Why are you outputting your script to /var/log/cron.log anyway? If you weren’t overwriting that file you would see the cron daemon log the execution of your script every minute in there instead.
– Darren
Feb 9 at 7:22
4
Look at the cron.log's time stamp with
ls -l var/log/cron.log. Notice anything?– Jens
Feb 9 at 11:34