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Help need in writing Regular Expression

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# 1  
Old 05-13-2009
Help need in writing Regular Expression
Hi
I need some help in writing a Regular expression.
I am getting Date format like "Tue Apr 12 8:21:20 2009" I want to change the this format to "Tue Apr 12 2009 8:21:20" using regular expression
Looking forward your help

Thanks
# 2  
Old 05-13-2009
how are you getting the date format in the first place.? from a file?
# 3  
Old 05-13-2009
Code:
bash-2.05b$ echo $DATE
Tue Apr 12 8:21:20 2009

bash-2.05b$ export NEWDATE=`echo $DATE | perl -pe '$_ =~ s/^(\w{3})\s+(\w{3})\s+(\d\d)\s+(\d+:\d+:\d+)\s+(\d{4})/$1 $2 $3 $5 $4/;'`

bash-2.05b$ echo $NEWDATE
Tue Apr 12 2009 8:21:20

bash-2.05b$

# 4  
Old 05-13-2009
if you are using date command straight from the command line, then use date +%Y etc and so on to format your date. check the man page of date for various format specifiers.
# 5  
Old 05-13-2009
Quote:
Originally Posted by TonySolarisAdmi
I am getting Date format like "Tue Apr 12 8:21:20 2009" I want to change the this format to "Tue Apr 12 2009 8:21:20" using regular expression
This is the "Shell Programming" forum, hence I assume you would like a shell based solution:

Code:
mydate="Tue Apr 12 8:21:20 2009"
year=${mydate##* }
mydate=${mydate% *}
prefix=${mydate% *}
postfix=${mydate##* }
mydate="$prefix $year $postfix"
echo $mydate

If you have access to ksh93 (on Solaris /usr/dt/bin/dtksh is ksh93 compatible):

Code:
#!/usr/dt/bin/dtksh
mydate="Tue Apr 12 8:21:20 2009"
mydate=${mydate/((?:??:??) (20??))/\3 \2}
print $mydate

I am puzzled about the need to surround the pattern at line 3 with additional brackets to make the backreferences work as expected.
I was heading for this
Code:
mydate=${mydate/(?:??:??) (20??)/\2 \1}

but for some reason this works only interactively and not in a script like the above.
# 6  
Old 05-13-2009
if OP's getting the date information from the date command, all he needs to do is give the correct output format
Code:
date "+%a %b %d %Y %H:%M:%S"

# 7  
Old 05-13-2009
I got it. Thanks a lot for your response.
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