I was wondering if there is a way to change the value of positional parameters inside a file.I mean, i want to change the value of a certain field of a file to the one i provide with?

i think this is more programming but you probably want to look into awk
possibly cut, grep, sed, paste, ... would also be helpful.

how to do it with awk? i am trying to serach a file on a certain field.when i find it i have to number those records using "for" loop,inside the awk command.
This is my file
A100:Annie Marie's Dance Academy:123:1500
F110:Frankies Repair Shop:1123:250
S100:Sandra's Counselling Service:67:500
A100:Annie Marie's Dance Academy:254:500

I need the output in a report form like this:
Vendor Name: Annie Marie's Dance Academy

1. Invoice #123 Amount: 1500
2. Invoice #254 Amount: 500

Here are the instructions:
It is recommended to use temporary files when matching valid vendor names to display the invoice and purchase amount information. You can then use command substitution and the set command to store vendor purchase information as positional parameters, and then use the for loop to display (hence number) each line...

I don't fully understand whether you want to CHANGE the values in the file, or SHOW the values from the file. Also, you already learned in another thread about this same exact subject, how to number the output lines using the NR variable from within `awk`. That thread is here: http://www.linuxquestions.org/questi...d.php?t=797911

Here's a way to SHOW the values; if you need to actually change them within the file, you'll want to use `sed` most likely.

Assuming the file you showed above is named "filename":
So, that just shows the entries for this vendor, which are inside the <filename>. To change the file, or put the results in a new file, I will leave that to you.

Also, I'll see about moving this thread to /programming, and/or joining it with its long lost friend, linked above

Sasha

My previuos posts were little confusing.Actually i wanna search the file based on the first field in this case "A100" which has 2 entries in this file.Then i want to output a report which gives the name name of the vendor once and the numbered list for the transactions associated with it.Presently i am searching for the specific entries, putting it in a temporary file and then displaying the report for that specific entries. e.g
my temp file is :
1. A100:Annie Marie's Dance Academy:123:1500
2. A100:Annie Marie's Dance Academy:254:500

then i am using the command:
awk -F ":" 'BEGIN{printf "Purchases Detail\n===============\n\n"}{printf "Vendors Name :%s\n",$2}{printf "Invoice# %i\t",$3}{printf "Amount:$%5.2f\n",$4}{print $1}' temp2

which is giving me this output:
Enter the vendor number: A100
Purchases Detail
=================

Vendors Name :Annie Marie's Dance Academy
Invoice# 123 Amount:$123.00
Vendors Name :Annie Marie's Dance Academy
Invoice# 254 Amount:$254.00

but i need this output:
Vendor Name: Annie Marie's Dance Academy

1. Invoice #123 Amount: 1500
2. Invoice #254 Amount: 500
Now the problem is how to store the value of second field in a variable by separating it from the entire file.

Thanks in advance

^ i am not so l33t with awk so i did it in two separate commands:

Thanks schneidz and grapefruitgirl for your help.I deeply appreciate your help.