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Date variable - 1 in UNIX

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# 1  
Old 01-29-2015
Date variable - 1 in UNIX
Hi,

I have a variable which stores a date value in my script. let that be todays_date. This holds a date value which is based on some other calculation not relevant here.

I need the value of todays_date-1..ie previous date to this value...is that possible?
# 2  
Old 01-29-2015
What operating system and shell are you using?

In what format is the date stored in your variable?
# 3  
Old 01-29-2015
Quote:
Originally Posted by Don Cragun
What operating system and shell are you using?

In what format is the date stored in your variable?
Sorry for not mentioning it earlier..

OS: AIX, shell - ksh
Format: yyyy-mm-dd
Eg. 2015-01-29
# 4  
Old 01-29-2015
Are you just looking for yesterday's date; or are you looking for the day before some arbitrary date?
# 5  
Old 01-29-2015
Quote:
Originally Posted by Don Cragun
Are you just looking for yesterday's date; or are you looking for the day before some arbitrary date?
No..I dont want yesterday's date ...it should be 1 day prior to the date stored in my variable...not sure if thats even possible or not..
# 6  
Old 01-29-2015
Hello siddharthmani,

Could you please try following code and let me know if this helps you.
Code:
cat scipt.ksh
echo $1 | awk -vs1="01" -vs2="03" -vs3="12" '{if(length($0)>8){print "Wrong Input!!";exit};YEAR=substr($0,1,4);YEAR+0;MONTH=substr($0,5,2);MONTH+0;DATE=substr($0,7,2);DATE+0;split("31 29 31 30 31 30 31 31 30 31 30 31", W," ");if(DATE==s1 && MONTH==s1){YEAR=YEAR-1; MONTH=12; DATE=31; print YEAR MONTH DATE}  else if(DATE==s1 && MONTH >= s1 && MONTH <= s3){MONTH=MONTH-1;W[2]=(YEAR%4!=0)?28:29;print YEAR MONTH W[MONTH]} else {DATE=DATE-1;printf("%04d%02d%02d\n", YEAR, MONTH, DATE)}}'

Now when we run the script as follows.
Code:
./script.ksh 20000101 #(Input should be passed in yyyymmdd manner)
19991231 #Is the output

Similar way you can pass your variable to this script.

EDIT: Adding a non oneliner form of same solution.
Code:
cat script.ksh
echo $1 | awk -vs1="01" -vs2="03" -vs3="12" '{
                                                if(length($0)>8){
                                                                        print "Wrong Input!!";
                                                                        exit
                                                                }
                                                YEAR=substr($0,1,4);
                                                YEAR+0;
                                                MONTH=substr($0,5,2);
                                                MONTH+0;
                                                DATE=substr($0,7,2);
                                                DATE+0;
                                                split("31 29 31 30 31 30 31 31 30 31 30 31", W," ");
                                                if(DATE==s1 && MONTH==s1){
                                                                                YEAR=YEAR-1;
                                                                                MONTH=12;
                                                                                DATE=31;
                                                                                print YEAR MONTH DATE
                                                                         }
                                                else if(DATE==s1 && MONTH >= s1 && MONTH <= s3){
                                                                                MONTH=MONTH-1;
                                                                                W[2]=(YEAR%4!=0)?28:29;
                                                                                print YEAR MONTH W[MONTH]
                                                                                                }
                                                else {
                                                                                DATE=DATE-1;
                                                                                printf("%04d%02d%02d\n", YEAR, MONTH, DATE);
                                                     }
                                              }'


Thanks,
R. Singh
Last edited by RavinderSingh13; 01-29-2015 at 03:36 AM.. Reason: Added a non one liner form of solution now
# 7  
Old 01-29-2015
Quote:
Originally Posted by RavinderSingh13
Hello siddharthmani,

Could you please try following code and let me know if this helps you.
Code:
cat scipt.ksh
echo $1 | awk -vs1="01" -vs2="03" -vs3="12" '{if(length($0)>8){print "Wrong Input!!";exit};YEAR=substr($0,1,4);YEAR+0;MONTH=substr($0,5,2);MONTH+0;DATE=substr($0,7,2);DATE+0;split("31 29 31 30 31 30 31 31 30 31 30 31", W," ");if(DATE==s1 && MONTH==s1){YEAR=YEAR-1; MONTH=12; DATE=31; print YEAR MONTH DATE}  else if(DATE==s1 && MONTH >= s1 && MONTH <= s3){MONTH=MONTH-1;W[2]=(YEAR%4!=0)?28:29;print YEAR MONTH W[MONTH]} else {DATE=DATE-1;printf("%04d%02d%02d\n", YEAR, MONTH, DATE)}}'

Now when we run the script as follows.
Code:
./script.ksh 20000101 #(Input should be passed in yyyymmdd manner)
19991231 #Is the output

Similar way you can pass your variable to this script.

EDIT: Adding a non oneliner form of same solution.
Code:
cat script.ksh
echo $1 | awk -vs1="01" -vs2="03" -vs3="12" '{
                                                if(length($0)>8){
                                                                        print "Wrong Input!!";
                                                                        exit
                                                                }
                                                YEAR=substr($0,1,4);
                                                YEAR+0;
                                                MONTH=substr($0,5,2);
                                                MONTH+0;
                                                DATE=substr($0,7,2);
                                                DATE+0;
                                                split("31 29 31 30 31 30 31 31 30 31 30 31", W," ");
                                                if(DATE==s1 && MONTH==s1){
                                                                                YEAR=YEAR-1;
                                                                                MONTH=12;
                                                                                DATE=31;
                                                                                print YEAR MONTH DATE
                                                                         }
                                                else if(DATE==s1 && MONTH >= s1 && MONTH <= s3){
                                                                                MONTH=MONTH-1;
                                                                                W[2]=(YEAR%4!=0)?28:29;
                                                                                print YEAR MONTH W[MONTH]
                                                                                                }
                                                else {
                                                                                DATE=DATE-1;
                                                                                printf("%04d%02d%02d\n", YEAR, MONTH, DATE);
                                                     }
                                              }'


Thanks,
R. Singh
hi,

Thanks for the reply..but i cant include another script for just this purpose..is it possible to include the same logic in my script?
also note i need to use this date in an sql query..so will that be possible?
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