Shell Programming and Scripting

I do something similar. I put the date into a file, but I rename the files to age them. I.E.:

Code:

mv day29 day30
mv day28 day29
...
mv day01 day02
date +%D > day_01

One other thing I do is run it at around 11:00am Mon to Fri, and I first check to see if there are at least 'x' users logged in. 'x' is 70% of my typical number of users. This way my dates only contain business dates, and automatically skip holidays and snow days.

When using them, I always selected TWO day files. I.E. check to see if my date is <= day06 and > day07, or something similar.

This has bothered me for a while and I think I finally found a real solution in Solaris using the expr command to do the math for you.

you have to find today's date and put it in a variable.

Code:

today=`date +%Y%m%d`

Then run the expr command to get yesterday's date or two days ago, etc.

Code:

yesterday=`expr $today - 1`
echo $yesterday

This should work or does at least in Solaris 10.

Will not work in general. On January 1 your technique will report that yesterday was January 0.

The clever shell scripter is using an undocumented feature of the time zone command. It worked for +48 and -168 when I tested, but adding a semicolon to end the command ruins it. The CST is "Central Standard Time".

Yesterday's working day

RE: Shell script problem for you...

Code:

((D=$(date +%w)+2))
if [ $D -gt 3 ]; then D=1; fi
YESTERDAY=`TZ="GMT+$((D*24))" date  +%Y%m%d`; echo $YESTERDAY

I usually compute:

Code:

$date --date="yesterday"

works with tomorrow too.

hello from Brazil! My english is not good but i will try...
Im a Ubuntu user and i got yesterday's date like this

(for yesterday)
date -d yesterday

(for 2 days ago)
date -d 2yesterday

you add days before the word "yesterday" and get how many days ago u want,

(for 100 days ago)
date -d 100yesterday

u can put the output format u want, as
date -d 1000yesterday +%Y-%m-%d-%Hh%M

and also u can do the same for next days, using "tomorrow"
date -d 1000tomorrow +%Y-%m-%d-%Hh%M