UNIX for Dummies Questions & Answers

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.

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

Thanks for the reply Corona.To conrirm, i wanted to append the numeric value by 1...


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.

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

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

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.

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..