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Top Forums Shell Programming and Scripting meaning of today=${1:-${today}} Post 302612715 by Vidhyaprakash on Monday 26th of March 2012 09:35:14 AM
Old 03-26-2012
meaning of today=${1:-${today}}

what does today=${1:-${today}} mean???

I saw a script which has these two lines:
today=`date '+%y%m%d'`
today=${1:-${today}}

but both gives the same value for $today

Code:
user:/export/home/user>today=`date '+%y%m%d'`
user:/export/home/user>echo $today
120326
user:/export/home/user>today=${1:-${today}}
user:/export/home/user>echo $today
120326
user:/export/home/user>today=
user:/export/home/user>today=${1:-${today}}
user:/export/home/user>echo $today
 
user:/export/home/user>

Can someone please let me know, what actually today=${1:-${today}}
means???
 
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calendar(1)						      General Commands Manual						       calendar(1)

Name
       calendar - calendar reminder service

Syntax
       calendar [-]

Description
       The  command  consults the file `calendar' in the current directory and prints out lines that contain today's or tomorrow's date.  The com-
       mand recognizes most month-day dates, such as Dec. 7, december 7, 12/7, but it does not recognize dates formatted in the following ways:  7
       December  or  7/12.  If you give the month as * with a date, such as, * 1, that day in any month will do.  On weekends, specifying tomorrow
       extends through Monday.

       When an argument is present, the command searches through a user's calendar file in his login directory and sends him any positive  results
       by Normally this is done daily under control of

       The  calendar  file  is	first  run  through  the  C  preprocessor, to include any other calendar files specified with the #include syntax.
       Included calendars are shared by all users, and are maintained and documented by the local administration.

Options
       -    Functions for every user who has a calendar file in his login directory.

Restrictions
       The extended idea of tomorrow does not account for holidays.

Files
       calendar
       /usr/lib/calendar to figure out today's and tomorrow's dates
       /etc/passwd
       /tmp/cal*
       /lib/cpp, egrep, sed, mail as subprocesses

See Also
       at(1), cron(8), mail(1)

																       calendar(1)

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