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NAME    [Toc]    [Back]

       crontab - Submits a schedule of commands to cron

SYNOPSIS    [Toc]    [Back]

       crontab [file]

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

STANDARDS    [Toc]    [Back]

       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    [Toc]    [Back]

       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

              [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

OPERANDS    [Toc]    [Back]

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

DESCRIPTION    [Toc]    [Back]

       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      command,      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 >

       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.


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

       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

       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 command  to  be

       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 standard 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    [Toc]    [Back]

       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    [Toc]    [Back]

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

EXAMPLES    [Toc]    [Back]

       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


       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 characters
 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    [Toc]    [Back]

       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    [Toc]    [Back]

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

       Files:  queuedefs(4)

       Standards:  standards(5)

[ Back ]
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