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Join Date: Oct 2007
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Newbie Poster
Challenging Script Hi all,
I have two files namely
a.txt
b.txt
a.txt contains 100 records and b.txt contains 9 records.These 9 records in b.txt is also present in a.txt.So,I need a script that compares these two files and outputs the unique 91 records alone in another file.
Thanks to all in advance!!!!
Regards
dave.
I have two files namely
a.txt
b.txt
a.txt contains 100 records and b.txt contains 9 records.These 9 records in b.txt is also present in a.txt.So,I need a script that compares these two files and outputs the unique 91 records alone in another file.
Thanks to all in advance!!!!
Regards
dave.
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Cool. What do you have so far, and what problem are you having with it.
Java Programmer and Sun Systems Administrator
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
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Newbie Poster
I am trying to do this.But i dont know how to do the comparison part.
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Newbie Poster
Also am trying this in microsoft Access.
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Originally Posted by dave_nithis 
Also am trying this in microsoft Access.
What do you mean by this? This forum is for Linux/Unix Shell Scripting, not Windows Batching (unless things have changed).
As far as doing the comparisons, an easy, but not necessarily performant way is a simple grep command.
Java Programmer and Sun Systems Administrator
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
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Posting Whiz
a's got 100
b's got 9
you need the 91 uniques - I'll put 'em in c.txt
Sorry - just needed to drop a post somewhere - it's been a while
, Mike
b's got 9
you need the 91 uniques - I'll put 'em in c.txt
while read line
do
grep $line b.txt >/dev/null 2>&1
if [ $? -ne 0 ]
then
echo $line >>c.txt
fi
done <a.txtSorry - just needed to drop a post somewhere - it's been a while
, Mike
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Originally Posted by eggi
a's got 100
b's got 9
you need the 91 uniques - I'll put 'em in c.txt
while read line do grep $line b.txt >/dev/null 2>&1 if [ $? -ne 0 ] then echo $line >>c.txt fi done <a.txt
Sorry - just needed to drop a post somewhere - it's been a while
, Mike
Its actually easier, if with a few more file operations.
cp b.txt /tmp/b1.txt while read line do grep -v $line /tmp/b1.txt >/tmp/b2.txt 2>/dev/null mv -f b2.txt b1.txt done <a.txt mv b1.txt c.txt
Last edited by masijade : Nov 17th, 2007 at 5:58 am.
Java Programmer and Sun Systems Administrator
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
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Newbie Poster
Masijade,
I finished the file comparison in MS Access.But I am trying to do the same file comparison using Shell script...Thats why posted you a thread..
I didn't understand this line in your script :
grep -v $line /tmp/b1.txt >/tmp/b2.txt 2>/dev/null
Can you please explain?
Thanks in advance
Regards
dave.....
I finished the file comparison in MS Access.But I am trying to do the same file comparison using Shell script...Thats why posted you a thread..
I didn't understand this line in your script :
grep -v $line /tmp/b1.txt >/tmp/b2.txt 2>/dev/null
Can you please explain?
Thanks in advance
Regards
dave.....
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Newbie Poster
Re: Challenging Script •
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Originally Posted by eggi
a's got 100
b's got 9
you need the 91 uniques - I'll put 'em in c.txt
while read line do grep $line b.txt >/dev/null 2>&1 if [ $? -ne 0 ] then echo $line >>c.txt fi done <a.txt
Sorry - just needed to drop a post somewhere - it's been a while
, Mike
Mike,
why are you using ">/dev/null 2>&1" in your script?
What condition you are checking in your "if" loop?
Regards
Dave
Last edited by dave_nithis : Nov 19th, 2007 at 7:57 am.
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Originally Posted by dave_nithis
Masijade,
I finished the file comparison in MS Access.But I am trying to do the same file comparison using Shell script...Thats why posted you a thread..
I didn't understand this line in your script :
grep -v $line /tmp/b1.txt >/tmp/b2.txt 2>/dev/null
Can you please explain?
Thanks in advance
Regards
dave.....
grep -v means to match everything except the next text (you should probably place $line in quotes) from the the first file listed (b1.txt) and output it to the second file listed ( > b2.txt) and ignore any error messages (2>/dev/null).
The next line then moves b2.txt to b1.txt so you can repeat the procedure with the next line. Once you have gone through all lines, b2.txt contains all lines from b that were not in a.
Java Programmer and Sun Systems Administrator
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
----------------------------------------------
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan
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