Calculating the difference between dates

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# 8  
Old 10-19-2009
I think what you are trying to say is that you need to calculate the difference between two dates and express that as a number of days, then pass the number to find's mtime option.

Is that it?
# 9  
Old 10-19-2009
Yes, just it!
# 10  
Old 10-19-2009
I will take a look at this later when I get home
In the meantime I have definitely seen posts here that give example code on how to subtract one date from another. Try searching for them. Smilie
# 11  
Old 10-19-2009
How to display the ascii characters in java using unix OS

The program is not able to converting the Hexa decimal characters into Ascii characers in Unix.

The same program when i run in Windows, displaying +j, but in unix dispalying different characters.

byte[] bytes = newbyte[hex.length()/2];

for(int i=0;i<bytes.length;i++){
bytes[i] = (
byte)Integer.parseInt(hex.substring(2*i, 2*i+2),16);
String multi =
new String(bytes);
out.println(" multi value from unHex method "+multi);

Please guide me what i have to do in unix?

# 12  
Old 10-19-2009
I don't think that UNIX has any built in functionality for doing date math but there are plenty of sites on the web detailing various ways of attacking it. I use a function written in C myself but I cannot give it to you as it was written for the company I work for so is copyrighted.

However here is a link to a site with a C program you can compile that will do date subtraction: -

Date math in Linux shell script? :: Free Tech Support :: Ask Dave Taylor!

There are also posts on this site that do it pretty well in shell if you aren't concerned about leap years and so on.

Good luck
# 13  
Old 10-19-2009

If you have GNU date then calculating the number of days from today is easy.
days_since() {
  echo $((($(date +%s)-$(date -d "$@" +%s))/3600/24))
me@tinybird:~$ days_since 20081019

# 14  
Old 10-19-2009
The late. lamented Bob Stockler of Louiville , KY left behind his brilliant collection of scripts that do arithmetic with dates.

They're on my ftp site,, in the /pub directory under the name datemath.tgz
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