Finding things on lines of a txt file

Jayfrin · 05-14-2008, 08:12 AM

Ok this may not make sense but I have a program which uses a while loop to search through a text file and I have a counter that records the line which it is on so what I need is that when it finds the first piece of desired data it then looks to the like right under that (counter number) and puts that in a variable.

Code:

data#1
data#2<this is the one i want to get when 
                 it gets the value of #1
data #3
data #4

Note : these lines arn't nessecarly line one & two the ycould be anywhere in the text file.

unSpawn · 05-14-2008, 09:08 AM

If you grep for text you can -A n next lines with it and how you get the numerical value into a variable from the counter line depends on if its fixed field or not if its not then you could test each element in the line while read line do for item in line do test -z ${item//[0-9]/} && echo $item done done prolly is an easier way btw notice how punctuation makes stuff easier to read at least i think so.

Jayfrin · 05-15-2008, 07:56 AM

I'm primitive and confused

matthewg42 · 05-15-2008, 08:13 AM

As unSpawn said, there is a command line option to the grep program which will help you do this.

You didn't state what programming language you are using, and you didn't post what code you have so far, so it's very hard to give you more precise help.

If you are writing a shell script, you don't need to read through the file with your own loop - it is more normal (and usually more efficient) to use grep or one of the other ubiquitous text processing programs (like sed, awk, tr, cut, paste, fold, head, tail etc). What if there is more than one line in the input file which has the search pattern in it? Do you want to do something for all the following lines, or just the first one? Perhaps this will help:

Code:

$ cat data
data#1 First line
data#2 Second line
data#3 Third line
data#4 Fourth line
$ grep -A 1 -m 1 "data#1" data |tail -1
data#2 Second line

You can assign the output of one program to a variable like this:

Code:

myvariablename=$(some command here)