grep -v while loop


 
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# 1  
Old 01-25-2007
Power grep -v while loop

alist contain:
a
b
c
d
e

blist contain:
a
b
c

the code:

#!/usr/bin/ksh
cat blist | while read line
do
grep -V "$line" alist > data
done

I expect to get

d
e

for my result but I don't. What is wrong?
# 2  
Old 01-25-2007
Quote:
Originally Posted by bobo
alist contain:
a
b
c
d
e

blist contain:
a
b
c

the code:

#!/usr/bin/ksh
cat blist | while read line
do
grep -V "$line" alist > data
done

I expect to get

d
e

for my result but I don't. What is wrong?
I would expect you output to be:
b
c
d
e
f
a
c
d
e
f
a
b
d
e

and have no Idea why you are doing something so convoluted, since you appear to be attempting to replicate the behaviour of fgrep -v (or grep -vf)
# 3  
Old 01-25-2007
Data Please advise!

What I try to do is to get the different between alist and blist; in this case the result should be:

d
e

My alist is unknown list of data and so is blist. Let's say my alist contains:

e
b
c
a
d

and my blist contains:

c
a
b


Using the code that I have:

#!/usr/bin/ksh
cat blist | while read line
do
grep -V "$line" alist > data
done

What do I have to do to have a data file that contain:

e
d

Please advise! I tried "diff" it is not worked!
# 4  
Old 01-25-2007
maybe you have a typo?? its supposed to be grep -v with small 'v', not 'V' ??
# 5  
Old 01-26-2007
Quote:
Originally Posted by bobo
Using the code that I have:
Code:
#!/usr/bin/ksh
cat blist | while read line
do
  grep -V "$line" alist > data
done

What do I have to do to have a data file that contain:

e
d

Please advise! I tried "diff" it is not worked!
Try this:

Code:
#!/usr/bin/ksh

# mydiff: gets the diff of two files and writes
# the difference to a third file.

cp alist data

cat blist |
while read line
do
  grep -v "$line" data > /tmp/data
  mv /tmp/data data
done

# end mydiff

# 6  
Old 01-26-2007
MySQL Mechanicly clever!

It works! Thanks! Are there other ways??? any else?
thanks!
# 7  
Old 01-26-2007
Quote:
Originally Posted by bobo
It works! Thanks! Are there other ways??? any else?
thanks!
Code:
comm -3 file1 file2

Sort the files and then use the above command
 
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