How to get previous year and previous month in solaris 8

Question

How to get previous year and previous month in solaris 8?

I have tried below command but none of them is correct:

date +'%m' -d 'last month'
date +'%Y' -d 'last year'

Solution 1

Solaris date does not support -d option like GNU date.

You can use perl:

$ perl -MPOSIX=strftime -le '@t = localtime; $t[3] = 1; $t[4]--; print strftime("%m", @t)'
05    
$ perl -MPOSIX=strftime -le '@t = localtime; $t[3] = 1; $t[5]--; print strftime("%Y", @t)'
2013

Or if you have ksh93:

$ printf "%(%m)T\n" "last month"
05  
$ printf "%(%Y)T\n" "last year"
2013

Updated

For @glennjackman's comment, I found a documentation in Time::Piece module:

   The months and years can be negative for subtractions. Note that there is some "strange" behaviour when adding and subtracting months
   at the ends of months. Generally when the resulting month is shorter than the starting month then the number of overlap days is
   added. For example subtracting a month from 2008-03-31 will not result in 2008-02-31 as this is an impossible date. Instead you will
   get 2008-03-02. This appears to be consistent with other date manipulation tools.

Because the OP only want to get previous year and month, we can set $t[3] = 1 to fix this problem.

Solution 2

A corrective to the perl idea (There is a problem with that solution in the month of January, yes?).

The last month is:

$ perl -MPOSIX=strftime -le '@t = localtime; @l = localtime (time - @t[3] * 86400); print strftime("%m", @l)'

Comments

[cuonglm]

What command did you use?

[Kumar1]

date +'%m' -d 'last month' date +'%Y' -d 'last year'

[jw013]

As far as I know only the GNU version of date has a -d option that accepts input like last month or last year.

[lornix]

expr $(date +%m) - 1 and expr $(date +%Y) - 1 work well too.

[Kumar1]

Thanks @lornix , for previous year "expr $(date +%Y) - 1" command works for me . but for month am expecting result in standard numerical format like 05,06,07...any suggestion ?

[lornix]

The leading zero is going to cause issues with 08 & 09 (octal value implied by leading zero)... but ok.... printf "%02d" $(expr $(date +%-m) - 1) should produce the output you're looking for. (The %-m tells date to not pad with zeros, avoiding the octal problem during the printf operation)

[Angel Todorov]

+1 for the perl suggestion. It's not foolproof though, March 30 minus one month will give you March 2 (Feb 30 is assumed to be Feb 28 plus 2 days, in a non-leap year). Date arithmetic can be odd.

[cuonglm]

@glennjackman: I updated my answer to work around this problem, just set the date to 1.