Why is crond failing to run a non-root crontab on alpine linux?

Question

I created this test bash script

#! /bin/bash
echo "hello"
mkdir "/karan/washere"

cron job i created, i want to run this cron job to run every min and want the log

#testing if cron job workes or not
1 * * * * /user/local/bin/bash /root/test.sh &> /root/crontest.log

I also have given the permission for the script, using

sudo chmod u+x test.sh

I tried to log the syslog using

sudo grep CRON /var/log/syslog

but didn’t show there also,

let me know if you need any more info or other context,

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Unless you’ve skipped some characters when writting the syslog output in your question, it looks like you’ve made a typo in your CRON command by forgetting the / in front of the command that should looks like :

/home/wayne/scripts/mysql_backup.sh

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• Mysql backup scripts not running as root crontab — help

  I’m trying to run a crontab as root but the script is not running successfully. I can see in syslog that the script is executing but it does not finish.

  MyUSER="root" # USERNAME
  MyPASS="devan13" # PASSWORD
  MyHOST="localhost" # Hostname
  # Linux bin paths, change this if it can not be autodetected via which command
  MYSQL="$(which mysql)"
  MYSQLDUMP="$(which mysqldump)"
  CHOWN="$(which chown)"
  CHMOD="$(which chmod)"
  GZIP="$(which gzip)"
  # Backup Dest directory, change this if you have someother location
  DEST="/home/wayne/backup"
  # Main directory where backup will be stored
  MBD="$DEST/mysql"
  # Get hostname
  HOST="$(hostname)"
  # Get data in dd-mm-yyyy format
  NOW="$(date +"%d-%m-%Y")"
  # File to store current backup file
  FILE=""
  # Store list of databases
  DBS=""
  # DO NOT BACKUP these databases
  IGGY="thisdatabaseschema thatdatabase herdata mydata"
  [ ! -d $MBD ] && mkdir -p $MBD || :
  # Only root can access it!
  $CHOWN 0.0 -R $DEST
  $CHMOD 0600 $DEST
  # Get all database list first
  DBS="$($MYSQL -u $MyUSER -h $MyHOST -p$MyPASS -Bse 'show databases')"
  for db in $DBS
  do
  skipdb=-1
  if [ "$IGGY" != "" ];
  then
  for i in $IGGY
  do
  [ "$db" == "$i" ] && skipdb=1 || :
  done
  fi
  if [ "$skipdb" == "-1" ] ; then
  FILE="$MBD/$db.$HOST.$NOW.gz"
  # do all inone job in pipe,
  # connect to mysql using mysqldump for select mysql database
  # and pipe it out to gz file in backup dir :)
  $MYSQLDUMP --quick -u $MyUSER -h $MyHOST -p$MyPASS $db | $GZIP -9 > $FILE
  fi
  done

  • I hope your mysql password is not actually ‘devan13’. If so, you’ll probably want to change it now that you’ve posted it in a public forum.

  • I suggest adding a shebang (#!/bin/bash) as the first line of your script.

I am having a nasty time running a non-root crontab file on Alpine Linux.

Here is the setup.

My crontab looks like this:

PATH=/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/opt/aws/bin:/home/ec2-user/bin
SHELL=/bin/bash
* * * * * /opt/monitor/monitor.sh >> /var/log/monitor.log 2>&1
0 3 * * * /opt/monitor/monitor-log-clean.sh >> /var/log/monitor.log 2>&1

FROM alpine:3.5
# DEPENDENCY TO ALLOW USERS TO RUN crontab -e
RUN apk add --update busybox-suid
# I LIKE BASH
RUN apk --no-cache add bash bash-doc
RUN apk --no-cache add util-linux pciutils usbutils coreutils binutils findutils grep
#... lots of custom stuff ...
# CREATE USER
RUN adduser -S robuser && \ mkdir -p /home/robuser
# ADD ENTRY POINT
ADD src/entrypoint.sh /home/robuser/entrypoint.sh
# GIVE MY USER ACCESS
RUN mkdir /etc/cron.d
RUN echo "robuser" > /etc/cron.allow
RUN echo "" >> /etc/cron.allow
RUN chmod -R 644 /etc/cron.d
# ADD MY CRONTAB
RUN mkdir -p /var/spool/cron/crontabs
ADD ./src/crontab.conf /tmp/cloudwatch/crontab.conf
RUN crontab -u robuser /tmp/cloudwatch/crontab.conf
# DEBUG... GIVE MY USER ACCESS TO EVERYTHING
RUN chown -R robuser /etc/cron.d
RUN chmod -R 755 /etc/cron.d
RUN chown -R robuser /var/spool/cron
RUN chmod -R 744 /var/spool/cron
RUN chown robuser /var/spool/cron/crontabs
RUN chmod 744 /var/spool/cron/crontabs
RUN chown -R robuser /etc/crontabs
RUN chmod -R 744 /etc/crontabs
RUN chown robuser /etc/crontabs/robuser
RUN chmod -R 744 /etc/crontabs/robuser
RUN chmod 600 /var/spool/cron/crontabs/robuser
# ADD MY MONITORING PROGRAM
RUN mkdir -p /opt/monitor
ADD src/monitor /opt/monitor
RUN mkdir -p /opt/monitor/.tmp && \ chown -R robuser /opt/monitor && \ chmod -R 700 /opt/monitor
RUN touch /var/log/entrypoint.log && \ touch /var/log/monitor.log && \ touch /var/log/cron.log && \ touch /var/log/awslogs.log && \ chown -R robuser /var/log
USER robuser
ENTRYPOINT /home/robuser/entrypoint.sh

meanwhile, my entrypoint.sh has this somewhere in it. I start the cron daemon as a background service and log to cron.log verbosely. I’ve also tried specifying -d 0 to get even more debug, but the didn’t really add anything to the output.

#!/bin/bash
crond -b -l 0 -L /var/log/cron.log
#... lots of other startup stuff ...

If I check the cron.log, its pretty empty:

crond: crond (busybox 1.25.1) started, log level 0
crond: wakeup dt=45
crond: wakeup dt=60
crond: wakeup dt=60

Meanwhile, /var/log/monitor.log is completely empty (see crontab at the beginning of the post).

So crond is not printing any errors.

I’ve tried everything i can think of to debug this. There’s no error message. It simply runs and never prints. A good suggestion was to simply my crontab.. but this also did not work:

PATH=/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/opt/aws/bin:/home/ec2-user/bin
SHELL=/bin/bash
* * * * * touch /tmp/test.txt

I’ve tried searching for other alpine containers who use non-root cron, but most people don’t go through the trouble of getting their alpine containers to run non-root.

Does anyone have any further suggestions to help debug this?

Тема: Запуск программы в crontab с правами root  (Прочитано 23057 раз)

0 Пользователей и 2 Гостей просматривают эту тему.

Solution 1

I have three solution suggestions for you.

1. Invoke the crontab with crontab -e -u root

2. Make sure that you have an empty line at the end of the cronjob file, meaning that every line ends with a newline.

3. You might need to redirect the output to devnull: shutdown -r now > /dev/null

Here are two helpful webpages for cronjobs:

You can also handle the cronjobs neatly with webmin.

Other than that, you have at least two more ways for restarting your computer at midnight.

One is to run the shutdown command as a script automatically at login but with specific time as a parameter instead of «now»:

shutdown -r 00:00

However, this will yield a broadcast message of upcoming shutdown at every login (might not be a bad thing at all). Well you can also make this be run at boot time by adding the script in init.d, still yielding the message, though.

Another is to use atcommand:

Enter command shutdown -r now and save it with ctrl+d or do a script for the command and do:

at -f restart_script.sh 0am

Hope these help you to get the result you wanted.

Solution 2

System Cron jobs are listed in /etc/crontab file. Therefore editing this file directly will help you out to run the reboot command as root.

$ sudo vi /etc/crontab
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user-name command to be executed 23 20 * * * root shutdown -r now

make sure you check the Cron log file after editing the crontab as it will let you know if the cron was installed successfully.

I have tested it and it worked for me. Restarted my system at 8:23 PM

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Comments

• I’m building a CNN with Keras that predicts the coordinates of 13 keypoints in every image. The images I have vary in input dimension so my input layer shape is (None, None, 3). I am using Inception Modules so I am using the Functional API. Now, while coding the last layers for my model, I encountered a problem. As far as I know, my output layer wil be a Dense(26) layer, since I will encode the x and y coordinates as a vector. I have trouble connecting the output layer with the preceeding Convolutional layers (because of tensor dimensions)

  x = Input(None, None, 3)
  stage_1 = Conv2D(26, (1, 1))(x)
  stage_1 = Dropout(0.3)(stage_1)
  stage_2 = Conv2D(512, (1, 1))(x)
  stage_2 = Dropout(0.3)(stage_2)
  stage_2 = Activation('relu')(stage_2)
  x = concatenate([stage_1, stage_2])
  x = Lambda(lambda i: K.batch_flatten(i))(x)
  outputs = Dense(26)(x)

  I tried including a Flatten Layer (but it is not compatible with arbitrary input shapes) and I’ve tried using K.batch_flatten() in a Lambda layer (which also did not work.) My question is: Is there a different way to get an output layer in a similar shape ((13,2) would also be fine, I just only found models online where the output layer is a Dense layer)? I also tried GlobalAveragePooling2d(), but this greatly decreased the accuracy of the model. Also, using a function to find the output shape did not work, see below

  stage_1 = Conv2D(26, (1, 1))(x)
  stage_1 = Dropout(0.3)(stage_1)
  stage_2 = Conv2D(512, (1, 1))(x)
  stage_2 = Dropout(0.3)(stage_2)
  stage_2 = Activation('relu')(stage_2)
  x = concatenate([stage_1, stage_2])
  def output_shape_batch(tensor_shape): print(tensor_shape) return (batch_size, tensor_shape[1] * tensor_shape[2] * tensor_shape[3])
  x = Lambda(lambda i: K.batch_flatten(i), output_shape=output_shape_batch)(x)
  outputs = Dense(26)(x)

  I expect the model to compile, but get TypeErrors
  The error is:
  TypeError: unsupported operand type(s) for *: ‘NoneType’ and ‘NoneType’

  • Why is this tagged debian? If this is about Debian and not Ubuntu, please ask on Unix & Linux.

  • Because debian is at the core of Ubuntu I believe.

• Not true! Cron does not use 12 hour time format and the format is always mm hh DD MM WD.

• The solution was to output to dev null. I wonder why?

• Please read the whole post next time.