CRON(8)                                                                CRON(8)



NAME
       cron - clock daemon

SYNOPSIS
       /etc/cron

DESCRIPTION
       _C_r_o_n  executes  commands  at specified dates and times according to the
       instructions in the files /usr/lib/crontab and  /usr/lib/crontab.local.
       None,  either  one,  or both of these files may be present.  Since _c_r_o_n
       never exits, it should only be executed once.  This  is  best  done  by
       running  _c_r_o_n from the initialization process through the file /etc/rc;
       see _i_n_i_t(8).

       The crontab files consist of lines of seven fields  each.   The  fields
       are  separated  by spaces or tabs.  The first five are integer patterns
       to specify:

       · minute (0-59)

       · hour (0-23)

       · day of the month (1-31)

       · month of the year (1-12)

       · day of the week (1-7 with 1 = Monday)

       Each of these patterns may contain:

       · a number in the range above

       · two numbers separated by a minus meaning a range inclusive

       · a list of numbers separated by commas meaning any of the numbers

       · an asterisk meaning all legal values

       The sixth field is a user name: the  command  will  be  run  with  that
       user’s uid and permissions.  The seventh field consists of all the text
       on a line following the sixth field, including spaces  and  tabs;  this
       text  is  treated  as  a  command which is executed by the Shell at the
       specified times.  A percent character (‘‘%’’) in this field  is  trans‐
       lated to a new-line character.

       Both crontab files are checked by _c_r_o_n every minute, on the minute.

FILES
       /usr/lib/crontab
       /usr/lib/crontab.local



7th Edition                      May 16, 1986                          CRON(8)