crontab(1)						      General Commands Manual							crontab(1)

NAME

       crontab - Submits a schedule of commands to cron

SYNOPSIS

       crontab [file]

       crontab -l  | -v  | -r  | -e [username]

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       crontab:  XCU5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

OPTIONS

       Edits  a copy of your crontab entry.  If the crontab entry does not exist, creates an empty entry to edit. The -e option invokes the editor
       specified by the EDITOR environment variable, or uses /usr/bin/vi by default.  The crontab command installs the new entry when  editing	is
       complete.

	      [Tru64  UNIX]  If  username  is  specified, edits the file for the specified user.  You must have appropriate privileges to use this
	      option.  Displays the contents of your crontab file.  Removes the crontab file from the crontab directory.   [Tru64  UNIX]  Displays
	      the name of your crontab file and the date and time at which you submitted it with crontab.

OPERANDS

       Path name of file that contains crontab specifications in the format described.

DESCRIPTION

       The  crontab  command copies the specified file or standard input if you do not specify a file into the /var/spool/cron/crontabs directory,
       which holds all users' crontab files.

       The cron command runs commands according to the instructions in the crontab files.  The crontab files are named for users, and the commands
       in  the	files  are run under the user's authority.  For example, the commands in the /var/spool/cron/crontabs/root file are run under root
       authority.  When you use the crontab command, the file under your authority is affected.  For example, if adm invokes the crontab  -l  com-
       mand,  the  /var/spool/cron/crontabs/adm  file  is  displayed.	If the username argument is included, the specified user's crontab file is
       listed and edited rather than the current user's crontab file.  You must have  root  privileges	to  specify  the  username  argument.	By
       default, the vi editor is used.

       Note  that  the file /var/spool/cron/crontabs/root contains several entries that will run by default, such as the following command to back
       up and clean the /var/adm/wtmp log file: 0 2 * * 0 /usr/bin/logclean /var/adm/wtmp > dev/null

       You can configure these default commands to suit your local system requirements.

       After cron runs commands according to the contents of your crontab file, it mails you the output from standard output  and  standard  error
       for these commands, unless you redirect standard output or standard error.

									  Note

       When entries are made to a crontab file by using the crontab command, all previous entries in the file are removed.

       You  can  use the crontab command if your user name appears in the /usr/lib/cron/cron.allow file.  If that file does not exist, the crontab
       command checks the /usr/lib/cron/cron.deny file to determine if you should be denied access to crontab.	The allow/deny files  contain  one
       user name per line.  If neither file exists, you can submit a job only if you are operating with superuser authority.

       Each crontab file entry consists of a line with six fields, separated by spaces and tabs.  The information in the fields specifies when the
       command runs and the name of the command.  The fields specify the following: The first field specifies the minute  (0 to 59).   The  second
       field specifies the hour (0 to 23).  The third field specifies the day of the month (1 to 31).  The fourth field specifies the month of the
       year (1 to 12).	The fifth field specifies the day of the week (0 to 6 for Sunday to Saturday).	The sixth field specifies the  shell  com-
       mand to be executed.

       You can specify the following values in the fields that indicate the time: An integer (within the appropriate range of values) Two integers
       separated by a dash to indicate an inclusive range A list of integers separated by commas An asterisk to select all possible values

       You can specify the days on which the command is to execute in two fields (day of the month and day of the week).   You	can  specify  both
       fields,	or you can specify only one field.  To use only one field to specify the days, the other field should contain an asterisk (*).	If
       both methods are used, the command is executed whenever either of the specifications is met.

       [Tru64 UNIX]  For example, the following entry runs command at midnight on the first and fifteenth days of each month,  as  well  as  every
       Monday: 0 0 1,15 * 1 command

       The  cron program runs the command named in the sixth field at the specified date and time.  If you include a percent sign (%) in the sixth
       field, cron treats everything that precedes it (in that field) as the command invocation, and makes all that follows it available to  stan-
       dard input, unless you escape the percent sign (\%) or double quote it ("%").  An exclamation point (!) in the sixth field is translated as
       a newline character.

       The shell runs only the first line of the command field (up to a percent sign or End-of-Line).  All other lines are made available  to  the
       command as standard input.

       The  cron  program  invokes a subshell from your $HOME directory.  This means that it will not run your file.  If you schedule a command to
       run when you are not logged in and you want to have commands in your run, you must explicitly do so in  the  crontab  file.   (For  a  more
       detailed discussion of how sh can be invoked, see the sh command.)

       The cron program supplies a default environment for every shell, defining HOME, LOGNAME, SHELL (=/usr/bin/sh), and PATH (=:/usr/bin).

       [Tru64  UNIX]  To submit commands to the cron daemon, invoke the crontab command with the -e option, or perform the following tasks: [Tru64
       UNIX]  Become the user that corresponds to the appropriate file in the /usr/spool/cron/crontabs directory.  For example,  if  you  want	to
       submit  commands  that will run under adm authority, become user adm.  [Tru64 UNIX]  Use the crontab command with the -l option to copy the
       appropriate file from the /usr/spool/cron/crontabs directory to a temporary file in your home directory.  For example, if you are user adm,
       you  could use the following command: crontab -l > temp_adm [Tru64 UNIX]  Edit the temporary file and add the commands you want to run at a
       specified time.	[Tru64 UNIX]  Use the crontab command and specify the temporary file to submit the commands to the cron daemon.

NOTES

       When entries are made to a crontab file, all previous entries are erased.  If your user ID is associated with  more  than  one  user  name,
       crontab	uses  the first user name that appears in the /etc/passwd file, regardless of which user name you might actually be using.  [Tru64
       UNIX]  The file /usr/lib/cron is a symbolic link to /var/adm/cron.  [Tru64 UNIX]  If cron.allow exists,	the  superuser's  user	name  must
       appear there for that superuser to be able to use the command.

EXIT STATUS

       The following exit values are returned: Successful completion.  An error occurred.

EXAMPLES

       The following example writes the time to the console every hour on the hour: 0 * * * * echo The hour is `date`. >/dev/console The following
       example runs calendar at 6:30 a.m. every Monday, Wednesday, and Friday: 30 6 * * 1,3,5 /usr/bin/calendar - The following example writes the
       contents  of happyholidays.txt to all users logged in at 4:00 p.m. each Friday in December and each day between December 10 and December 31
       inclusive: 0 16 10-31 12 5 /usr/sbin/wall /var/tmp/happyholidays.txt

ENVIRONMENT VARIABLES

       The following environment variables affect the execution of crontab: Determines the editor used with the -e  option.   Provides	a  default
       value  for  the	internationalization  variables that are unset or null. If LANG is unset or null, the corresponding value from the default
       locale is used. If any of the internationalization variables contain an invalid setting, the utility behaves as if none	of  the  variables
       had  been  defined.   If set to a non-empty string value, overrides the values of all the other internationalization variables.	Determines
       the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multibyte  char-
       acters  in arguments).  Determines the locale for the format and contents of diagnostic messages written to standard error.  Determines the
       location of message catalogues for the processing of LC_MESSAGES.

FILES

       Main cron directory.  Directory containing the crontab files adm, cronuucp, root, sys,and uucp.	List of allowed  users.   List	of  denied
       users.  Log of cron activity.  Queue description file for at, batch, and cron.  Contains user information.  User profile.

SEE ALSO

       Commands:  at(1), cron(8), mail(1), mailx(1), Bourne shell sh(1b), POSIX shell sh(1p)

       Files:  queuedefs(4)

       Standards:  standards(5)

																	crontab(1)