cron -- NCM component to control cron entries for Linux and Solaris.


The cron component manages files in the /etc/cron.d directory on Linux and the /var/spool/cron/crontabs directory on Solaris.


Files managed by ncm-cron will have the ncm-cron.cron suffix. Other files in the directory are not affected by this component. The name of each file will be taken from the nlist name.


Solaris uses an older version of cron that does not make use of a cron.d directory for crontabs. Ncm-cron shares the crontab with each user. To make this work ncm-cron uses the concept of separate file sections within the crontab. Each section is identified by the use of the tags NCM-CRON BEGIN: and NCM-CRON END:. Entries either side of these section identifiers are not modified.

Solaris does have a /etc/cron.d directory, however it uses this directory for control files such as cron.allow and cron.deny.



A list containing cron structures (described above).


Each cron entry in the /software/components/cron/entries list may contain the properties and resources described below. One of "frequency" or "timing" must be specified.

  • command : string (required)

    Command line to execute, including all its options.

    Default : None

  • comment : string (optional)

    An optional comment to add at the beginning of the cron file.

    Default : None

  • env : nlist (optional)

    An optional nlist containing environment variable that must be defined before executing the command. Key is the variable name, value is variable value.

    Default : None

  • frequency : string (optional)

    Execution frequency for the command, using standard cron syntax. Minutes field can be 'AUTO' : in this case, a random value between 0 and 59 inclusive is generated. This can be used to avoid too many machines executing the same cron at the same time. See also the "timing" element.

    Default : None

  • group : string (optional)

    Group to use to run the command. Defaults to user's primary group.

    Default : user's primary group

  • log : nlist (optional)

    A nlist allowing to define specific attributes for cron log file. Supported attributes are :

    • name

      name of the log file. If the name is not an absolute file name, file is created in /var/log. Default name is the cron file name with .log extension in /var/log.

    • owner

      owner/group of the log file, using owner:group format. group can be ommitted.

    • mode

      permissions of log file specified as a string interpreted as an octal number.

    • disabled

      A boolean value disabling the redirection of script output/error to a log file

  • name : string (required)

    Name of the cron entry file to create.

    Default : None

  • timing : nlist (optional)

    If the 'timing' nlist is used to specify the time, it can contain any of the keys: 'minute', 'hour', 'day', 'month' and 'weekday'. An unspecified key will have a value of '*'. A further key of 'smear' can be used to specify (in minutes) a maximum interval for smearing the start time, which can be as much as a day. When a smeared job is created, a random increment between zero and the smear time is applied to the start time of the job. If the start time results in the job running on the following day, then all other fields (day, weekday, etc) will be suitably modified. When smearing is specified, then the start minute (and possibly hour, if smear is more than one hour) must be specified as a simple absolute (e.g. '2') and cannot be variations such as lists or ranges. Time specifications such as ranges, lists and steps are supported except for named values (e.g. "1" must be used instead of "mon").

  • user : string (optional)

    User to use to run the command.

    Default : root


"/software/components/cron/entries" = list(
    "frequency", "*/2 * * * *",
    "command", "/bin/ls"),
    "comment", "some interesting text",
    "frequency", "*/2 * * * *",
    "command", "/bin/hostname"),
    "env", nlist("MAILTO", ""),
    "name", "date",
    "comment", "runs the date sometime within a 3 hour period",
    "timing", nlist(
        "minute", "0",
        "hour", "1",
        "smear", 180),
    "command", "/bin/date")

On Linux this will create three files in /etc/cron.d: ls.ncm-cron.cron hostname.ncm-cron.cron date.ncm-cron.cron

On Solaris three extra entries will be added to the root crontab.





None known.


Editing the NCM-CRON BEGIN: and/or the NCM-CRON END: tag within a crontab will cause unpredictable behaviour. Possible behavours are duplicate entries or entries being removed altogether.

Editing BETWEEN the tags will cause the edits to be overwritten the next time ncm-cron runs.

Charles Loomis


Guillaume Philippon <>

Mark Wilson