##############################################################
#
# The time and date fields are:
#
# field allowed values
# ----- --------------
# minute 0-59
# hour 0-23
# day of month 1-31
# month 1-12 (or names, see below)
# day of week 0-7 (0 or 7 is Sun, or use names)
#
# A field may be an asterisk (*), which always stands for ``first-last''.
#
# Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen.
# The specified range is inclusive. For example, 8-11 for an ``hours'' entry speci-
# fies execution at hours 8, 9, 10 and 11.
#
# Lists are allowed. A list is a set of numbers (or ranges) separated by commas.
# Examples: ``1,2,5,9'', ``0-4,8-12''.
#
# Step values can be used in conjunction with ranges. Following a range with
# ``/<number>'' specifies skips of the number's value through the range. For exam-
# ple, ``0-23/2'' can be used in the hours field to specify command execution every
# other hour (the alternative in the V7 standard is
# ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are also permitted after an asterisk,
# so if you want to say ``every two hours'', just use ``*/2''.
#
# Names can also be used for the ``month'' and ``day of week'' fields. Use the
# first three letters of the particular day or month (case doesn't matter). Ranges
# or lists of names are not allowed.
#
# The ``sixth'' field (the rest of the line) specifies the command to be run. The
# entire command portion of the line, up to a newline or % character, will be exe-
# cuted by /bin/sh or by the shell specified in the SHELL variable of the cronfile.
# Percent-signs (%) in the command, unless escaped with backslash (\), will be
# changed into newline characters, and all data after the first % will be sent to
# the command as standard input.
#
# Note: The day of a command's execution can be specified by two fields -- day of
# month, and day of week. If both fields are restricted (ie, aren't *), the command
# will be run when either field matches the current time. For example,
# ``30 4 1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th
# of each month, plus every Friday.
#
# EXAMPLES:
#
# # run five minutes after midnight, every day
# 5 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
# # run at 2:15pm on the first of every month -- output mailed to paul
# 15 14 1 * * $HOME/bin/monthly
# # run at 10 pm on weekdays, annoy Joe
# 0 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
# 23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
# 5 4 * * sun echo "run at 5 after 4 every sunday"
#
############################################################
#
# The time and date fields are:
#
# field allowed values
# ----- --------------
# minute 0-59
# hour 0-23
# day of month 1-31
# month 1-12 (or names, see below)
# day of week 0-7 (0 or 7 is Sun, or use names)
#
# A field may be an asterisk (*), which always stands for ``first-last''.
#
# Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen.
# The specified range is inclusive. For example, 8-11 for an ``hours'' entry speci-
# fies execution at hours 8, 9, 10 and 11.
#
# Lists are allowed. A list is a set of numbers (or ranges) separated by commas.
# Examples: ``1,2,5,9'', ``0-4,8-12''.
#
# Step values can be used in conjunction with ranges. Following a range with
# ``/<number>'' specifies skips of the number's value through the range. For exam-
# ple, ``0-23/2'' can be used in the hours field to specify command execution every
# other hour (the alternative in the V7 standard is
# ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are also permitted after an asterisk,
# so if you want to say ``every two hours'', just use ``*/2''.
#
# Names can also be used for the ``month'' and ``day of week'' fields. Use the
# first three letters of the particular day or month (case doesn't matter). Ranges
# or lists of names are not allowed.
#
# The ``sixth'' field (the rest of the line) specifies the command to be run. The
# entire command portion of the line, up to a newline or % character, will be exe-
# cuted by /bin/sh or by the shell specified in the SHELL variable of the cronfile.
# Percent-signs (%) in the command, unless escaped with backslash (\), will be
# changed into newline characters, and all data after the first % will be sent to
# the command as standard input.
#
# Note: The day of a command's execution can be specified by two fields -- day of
# month, and day of week. If both fields are restricted (ie, aren't *), the command
# will be run when either field matches the current time. For example,
# ``30 4 1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th
# of each month, plus every Friday.
#
# EXAMPLES:
#
# # run five minutes after midnight, every day
# 5 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
# # run at 2:15pm on the first of every month -- output mailed to paul
# 15 14 1 * * $HOME/bin/monthly
# # run at 10 pm on weekdays, annoy Joe
# 0 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
# 23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
# 5 4 * * sun echo "run at 5 after 4 every sunday"
#
############################################################
Hope this is useful to some of the linux beginners.