Replace date on a line with current date

Shell Programming and Scripting
1

Hi Guys,
I have a file with following content

From 20121014 : To 20121014
Number of days : 1 
1234
1245
1246
1111

Everyday i run my script i want to modify "To" date on the first line with current date. I have set the current date in script as

RUN_DATE=`date -u +%Y%m%d`

So i want to replace "To" date with $RUN_DATE. The "From" date never changes.
Also, i want to replace on second line (toDate-fromDate)+1. Right now it is 1. So when it runs tomorrow it should be 2.
Thanks - jak

2

Assuming, the line always be the first line..

awk 'NR==1 {$NF=date}1' date=$RUN_DATE file
3

Thanks clx - yes it will always be on 1st line. Also, how would i modify the second line with the difference between two days(numbers) + 1

Thanks for your help! _ jak

---------- Post updated at 02:47 PM ---------- Previous update was at 11:53 AM ----------

Correction on previous post. I need difference of two dates and not numbers update on line 2.

Thanks - jak

4

Do you have GNU date?

5

Yes. I tried this on my shell

date +"%Y%m%d" -d sunday 
20121021
6

Try...

awk ' NR == 1 {
              from = $2
              "date -u +%Y%m%d" | getline to
              $NF = to
      }
      NR == 2 {
              "expr $(date -d " to " +%s) - $(date -d " from " +%s)" | getline diff
              $NF = int(diff / 86400) + 1
      }
      {
              print $0
      }
      ' file1 > file2
7

Hi Ygor,

I tried and am getting this error when i run

sh: -c: line 0: syntax error near unexpected token `)'
sh: -c: line 0: ` +%s)'

thanks - jak

8

Use perl for date time calculations as the math would be incorrect when you run into the end of the month or year...

9

Works fine for me. What system are you on? Do you have nawk or gawk?

10

Hi Ygor,

I have awk and gawk.

uname -a
Linux 2.6.18-194.11.4.el5 #1 SMP Fri Sep 17 04:57:05 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
 whence awk
/usr/bin/awk

cat tmp.sh
#!/bin/ksh

STAT_FILE=myStats.txt
STAT_TMP_FILE=myStats.txt.tmp
 
awk ' NR == 1 {
              from = $2
              "date -u +%Y%m%d" | getline to
              $NF = to
      }
      NR == 2 {
              "expr $(date -d " to " +%s) - $(date -d " from " +%s)" | getline diff
              $NF = int(diff / 86400) + 1
      }
      {
              print $0
      }
      ' $STAT_TMP_FILE > $STAT_FILE

When i run

tmp.sh 
sh: -c: line 0: syntax error near unexpected token `)'
sh: -c: line 0: ` +%s)'

thanks - jak

---------- Post updated at 10:32 PM ---------- Previous update was at 02:01 PM ----------

I tried this on command line and it works fine

expr $(date -d " 20121016 " +%s) - $(date -d " 20121014 " +%s)

but inside the script i am getting the error

sh: -c: line 0: syntax error near unexpected token `)'
sh: -c: line 0: ` +%s) '

This line seems culprit

"expr $(date -d " to " +%s) - $(date -d " from " +%s) " | getline diff

Any other alternative to this particular line?
Thanks for your time and help - jak