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Old 11-16-2006, 07:50 PM   #1
WeiSomething
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How to extract data and for loop it into an array? (shell)


Hi everyone!


How do I do a split in UNIX? Like what a Java can do where it read in a file and split the data with the delimiter the user specified and put all the data it split into an array.


And how do I read a specific line in a file?

For example:

Data1

I love apple
I love orange
I love mango

How do i extract the second line "I love orange" out?
 
Old 11-16-2006, 09:10 PM   #2
unSpawn
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How do I do a split in UNIX? Like what a Java can do where it read in a file and split the data with the delimiter the user specified and put all the data it split into an array.
#Watch your IFS (delimiters)
Code:
ARRAY=(`output something`); 
echo ARRAY has ${#ARRAY[@]} elements.

And how do I read a specific line in a file?
Code:
cat file | while read line; do case "${line}" in *orange) doSomething;; esac; done
or
Code:
n=1; cat file | while read line; do [ $n -eq 2 ] && doSomething; ((n++)); done

Code:
function help() { echo "Bash scripting guides:
http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html 
http://www.tldp.org/LDP/Bash-Beginners-Guide/html/index.html 
http://www.tldp.org/LDP/abs/html/"; }
 
Old 11-16-2006, 11:56 PM   #3
WeiSomething
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Quote:
Originally Posted by unSpawn
How do I do a split in UNIX? Like what a Java can do where it read in a file and split the data with the delimiter the user specified and put all the data it split into an array.
#Watch your IFS (delimiters)
Code:
ARRAY=(`output something`); 
echo ARRAY has ${#ARRAY[@]} elements.
How do I set my IFS (delimiters) to an empty space?

file1
I love apple
I love orange
I love mango

Code:
ARRAY=(`more file1`); 
echo ARRAY has ${#ARRAY[@]} elements.
Does this print out "ARRAY has 9 elements."?

What I got is 1 element.
 
Old 11-17-2006, 12:39 AM   #4
Tinkster
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IFS='<something>'
It's a space by default, hence 9 elements. If you want one line = one element,
use IFS="\n"... if you see 1 element there's something seriously odd with your
system ...


Cheers,
Tink
 
Old 11-17-2006, 01:41 AM   #5
WeiSomething
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Registered: Nov 2006
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Quote:
Originally Posted by Tinkster
IFS='<something>'
It's a space by default, hence 9 elements. If you want one line = one element,
use IFS="\n"... if you see 1 element there's something seriously odd with your
system ...


Cheers,
Tink
hi. I know why I got only 1 element. Because I did not put any bracket around it. But after I put, it gave mi error like:

New1.sh[4]: syntax error at line 4 : `(' unexpected

ARRAY=(`more file1`); <-- this is the line that it prompt me with the error.
 
Old 11-17-2006, 02:45 AM   #6
WeiSomething
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Quote:
Originally Posted by WeiSomething
hi. I know why I got only 1 element. Because I did not put any bracket around it. But after I put, it gave mi error like:

New1.sh[4]: syntax error at line 4 : `(' unexpected

ARRAY=(`more file1`); <-- this is the line that it prompt me with the error.
I found out that the method is not correct in fact it should be:

Code:
set -A array1 `more test_file`
But now i had problem with the LFS because in my file there is space and new line. How to define 2 delimiters?
 
Old 11-17-2006, 03:27 AM   #7
bigearsbilly
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you can't have 2 delimiters. (not in ksh, which it looks like)

If you want to ignore blank lines
you can set -A array1 `grep . test_file`

you probably shouldn't really use 'more' as it's designed for interactive use
use 'cat' instead.

Last edited by bigearsbilly; 11-17-2006 at 03:28 AM.
 
  


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