awk file manipulation

[rogers42]

Hi,

I am new to awk and had the following questions w.r.t file manipulation

1, How do I read multiple files and search for common records (in the two or more files) ?

2, How can I exectue an awk utility with out having to specify an input file name at the command line ?

Thanks in advance.

rogers42

 

[feherke]

Hi

1, How do I read multiple files and search for common records (in the two or more files) ?

awk 'NR==FNR{v[$0]=1;next}v[$0]' /input/file1 /input/file2

[gray]# or[/gray]

gawk '{v[$0]++}END{for(l in v)if(v[l]==ARGIND)print l}' /input/file1 /input/file2 /input/filen

2, How can I exectue an awk utility with out having to specify an input file name at the command line ?

awk 'BEGIN{print"Hello World !"}'

Feherke.

http://rootshell.be/~feherke/

 

[rogers42]

Thanks faherke. Is it possible to read the contents of the first file (off the command line) while using "getline" function to read the second file ?

I am having problems with the following syntax

getline < file2

Thanks in advance.

rogers42

 

[feherke]

Hi

Is it possible to read the contents of the first file (off the command line) while using "getline" function to read the second file ?

I am having problems with the following syntax

getline < file2

Yes, it is possible. Would be better to see more from your code idea regarding where that line would placed. I think would be better to read those lines into another variable, not just in [tt]$0[/tt] :

getline [red]mystr[/red] < file2

Feherke.

http://rootshell.be/~feherke/

 

[p5wizard]

Also make sure that the file is in the current dir or specify full pathname. In any case enclose file name in double quotes like so...

getline mystr < "file2"

or

getline mystr < "/path/to/file2"

... and also that you have read persmission on that file2.



HTH,

p5wizard

 

[feherke]

Hi

Hmm... Yes, it is also possible. I just assumed that file2 is a variable. Good idea to mention it, p5wizard.

Feherke.

http://rootshell.be/~feherke/

 

[rogers42]

I have placed the following code in the file

{
while (( getline x < "file2.in") > 0)
print x
close("file2.in")
}

I am executing the utility as follows

awk -f multiple_files.awk

The utility complains of the following error

awk: syntax error near line 10
awk: illegal statement near line 10

The input file (file2.in) exists in the same directory and has read permission.

Any ideas as to what I might be doing wrong ?

Thanks in advance.

rogers42

 

[feherke]

Hi

I am executing the utility as follows

awk -f multiple_files.awk

And where is its input ?

[red]BEGIN[/red] {
   while (( getline x < "file2.in") > 0)
            print x
   close("file2.in")
}

[gray]# or[/gray]

awk -f multiple_files.awk [red]/input/file[/red]

By the way, your code works for me.

Feherke.

http://rootshell.be/~feherke/

 

[Annihilannic]

If you want to execute it without specifying an input file on the awk command line, you need to put your code in the BEGIN { } clause like in one of feherke's earlier examples. If you just put it in a { } section awk will assume you are providing some input from stdin.

Annihilannic.

 

[PHV]

And how an awk program of 5 lines (as you posted 9 May 07 12:58) may raise raise an error near line 10 ?

 

[rogers42]

Hi PHV,

The line numbers mismatch is becuase I had cut & paste the actual code minus the comments at the begining of the file.

Nice catch though

BTW, I am still struggling with the same syntax error. Others suggestions are more than welcome.

Thanks

rogers42

 

[PHV]

same syntax error
Again, WHICH LINE RAISES THE ERROR ?

 

[rogers42]

Hi,

while (( getline x < "file2.in") > 0)

Thanks

rogers42

 

[PHV]

No syntax error on this line for me.
Which flavor/version of awk ?
why not posting the whole content of multiple_files.awk ?

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[p5wizard]

just leave out the "> 0" part

while ( getline x < "file2.in")

HTH,

p5wizard

 

[PHV]

p5wizard, what happen with your suggestion if file2.in doesn't exist or isn't readable ?

 

[p5wizard]

PHV,

It loops infinitely reading an empty string... :~/
Serves me right for not testing thoroughly enough.

I omitted some parentheses on my first attempt and also got a syntax error. I then started off on a wild goose chase...

You are right, code as posted by rogers42 should work fine (it does in awk under AIX):

while (( getline x < "file2.in") > 0)

HTH,

p5wizard

 

[rogers42]

I am running awk on Solaris 8

Thanks

rogers42

 

[PHV]

Have you tried nawk instead ?

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[rogers42]

Yup, mystery partially solved !!!

"getline" in awk does not take an argument while the same function in nawk does. I.e. my code works in nawk.

I wonder why is the code working for almost all the other users in awk ? Maybe people are using a later version of awk ?

How can I check my awk version ?

Thanks

rogers42