Capturing some data from a file into a variable


 
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# 1  
Old 06-15-2006
Capturing some data from a file into a variable

I have a file with some values in a tab delimted format

Eg:
'test' contains:

a<tab>b<tab>c<tab>Trk_12345678

now i need to capture this value 'Trk_12345678' into a variable say 'x' and append that value of 12345678 to 12345679 and store is back to a new 'test1' file as :

'test1' contains:

a<tab>b<tab>c<tab>Trk_12345679

Can someone kindly help me on this.I kinda know u have to use commands like sed,cut etc..i jst need some insight of the exact usage.

Thanks.
shiroh_1982
# 2  
Old 06-15-2006
I'm not sure what you mean by 'append'. Are you always replacing the last digit by 9, which is not an append? Or are you adding 1 to the number, which is not an append either? or what?

Are you using the bash or sh shell? These scripts use bash built-in commands and string handlers, which are much faster than launching sed all the time. The IFS=$'\x09' tells it the data is tab-delimited, and the 'read' command reads each field into each variable listed after it. ${VAR4:offset:length} returns a substring of VAR4, ${VAR4:offset} returns the whole string after the given offset, and $((EXPR)) evaluates a mathematical expression.

This version just replaces the last digit by 9.
Code:
# IFS=$'\x09' read VAR1 VAR2 VAR3 VAR4 < test
# echo -e "${VAR1}\t${VAR2}\t${VAR3}\t${VAR4:0:11}9" > test1

This version adds 1 to the value.
Code:
# IFS=$'\x09' read VAR1 VAR2 VAR3 VAR4 < test
# X=${VAR4:4}
# echo -e "${VAR1}\t${VAR2}\t${VAR3}\tTrk_$((X+1))" > test1

# 3  
Old 06-16-2006
Thanks for the reply Corona.To conrirm, i wanted to append the numeric value by 1...

Quote:
Originally Posted by Corona688
This version adds 1 to the value.
Code:
# IFS=$'\x09' read VAR1 VAR2 VAR3 VAR4 < test
# X=${VAR4:4}
# echo -e "${VAR1}\t${VAR2}\t${VAR3}\tTrk_$((X+1))" > test1


I tried the same exact code you gave me but I was getting the following output:
a<tab>b<tab>c<tab>Trk_432511

Please note that in input was Trk_01514576.Another point to note is that id the input is Trk_01514576 ,i would like the output to be Trk_01514577.(please note the 0 in the header of the number has to be maintained)..

Thanks in advance.

Last edited by shiroh_1982; 06-16-2006 at 07:41 AM..
shiroh_1982
# 4  
Old 06-16-2006
Code:
[/tmp]$ cat try.ksh
#! /bin/ksh

val=\
"a      b       c       trk_012345678"
echo "$val"
num=${val##*_}
rest=${val%$num}
typeset -Z${#num} final
((num = num+1));
final=$num
echo "$rest$final"
[/tmp]$ ./try.ksh
a       b       c       trk_012345678
a       b       c       trk_012345679

If you want redirect the output to another file, then use
Code:
echo "$rest$final" > test1

# 5  
Old 06-16-2006
Thanks for the reply Vino...Im using the bash shell..

copied the code into vino.sh and when i ran that script got the following output:

./vino.sh

a b c trk_012345678
./vino.sh: typeset: unknown option: `-Z'
typeset: usage: typeset [-afFrxi] [-p] name[=value] ...
./vino.sh: ((: 012345678: value too great for base (error token is "012345678")
a b c trk_012345678
shiroh_1982
# 6  
Old 06-16-2006
Did you change the shebang #! /bin/ksh to #! /bin/bash

Dont you have ksh on your machine ? If you do, then do not change the shebang.
# 7  
Old 06-16-2006
I tried another way:

val=\
"a b c trk_012345678"
echo "$val"
num=${val##*_}
echo $num
rest=${val%$num}
echo $rest
final=`expr $num + 1`
echo "$rest$final"

However i still want to maintain that '0' in the header which gets ommited in the end..
shiroh_1982
 
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