awk is becoming real 'awk'ward

[Velvohm]

Hello,

I am having some trouble with awk or gawk for that matter. I want to write a script either in the command line or in a separate file that reads two pre-made files, say F1 and F2. The task is actually quite simple. It reads user -speciied columns/fields from F1 and F2 and prints them out as one record to another file called say F3. For instance, I want to read $1, $2 from F1 and $1 from F2. F3 should contain 3 columns: $1, $2 from F1 and $1 from F2. The problem is I cannot seem to make awk recognize the different fields in F1 and F2. Can anyone help me? thank you and please be specific as I am a novice awk user, as u probably can tell by this simple problem.

Cheers
velvohmmm

[VictorienSardou]

This script makes the ASSUMPTION that f1.txt and f2.txt have the same number of records ie the line count is the same.
Failure to maintain this will cause undefined output.

[root@lima awk]# cat prog.awk
BEGIN {FS=",";ORS=""}
{
if (FILENAME==ARGV[1]) {
getline <ARGV[1]
print $2,$3,""
getline <ARGV[2]
print $2,"\n"
} else {
exit
}
}
[root@lima awk]# cat f1.txt
q,w,e,r
a,s,d,f
z,x,c,v
[root@lima awk]# cat f2.txt
r,t,y
f,g,h
v,b,n
[root@lima awk]# awk -f prog.awk f1.txt f2.txt > f3.txt
[root@lima awk]# cat f3.txt
w e t
s d g
x c b
[root@lima awk]#

[Velvohm]

Thank you for this detailed explanation. Although, I solved the problem, I was wondering how to do with command line arguments and you seemed to have hit the hail dead on. Take care

Cheers
velvohm

[Velvohm]

Sorry to bother you but do u know how to make the above program as an executable. I have tried adding just the lines
#!/bin/awk -f to make an awk executable or just the lines #!/bin/sh awk ' ......prog.awk.... ' to the file prog.awk to make a shell executable but it keeps giving me annoying errors.

Thanks

Velvohm

[VictorienSardou]

glad to help, i am happy you liked the script.
not sure what you are doing but this works for me.

[root@lima awk]# chmod +x prog.awk
[root@lima awk]# cat prog.awk
#!/usr/bin/awk -f
BEGIN {FS=",";ORS=""}
{
if (FILENAME==ARGV[1]) {
getline <ARGV[1]
print $2,$3,""
getline <ARGV[2]
print $2,"\n"
} else {
exit
}
}
[root@lima awk]# ./prog.awk f1.txt f2.txt
w e t
s d g
x c b
[root@lima awk]#

[Velvohm]

Thanx for prompt reply. I had to make some changes because your code was working assuming both files were of same size. But finally got it working.

Cheers
Mowly

Oh because you were curious, I need this code for network evaluation using NS-2. that is all