Shell Programming and Scripting

Hi all,

I have an gawk script to get user's input, So I use

getline name < "-" (or getline name < "/dev/stdin") in my script

They both work fine when my script deals with files. But it is broken for pipes.
When I try "some command | my awk script", the variable name just gets an empty value (""), it does not get the value from stdin at all.

Why is that ? And how do I fix it ?

as far as i know get line deals with following six varients

Code:

getline 
sets $0, NF, FNR, and NR. 
getline var 
sets var, FNR, and NR. 
getline < file 
sets $0, and NF. 
getline var < file 
sets var. 
command | getline 
sets $0, and NF. 
command | getline var 
sets var.

no where its mentioned that it take i/p from stdin

It mentions in gawk user's guide The GNU Awk User's Guide
(seach "-").

And it works for files processing. Just seems not work for pipe.

Buddy that means
if getline < "filename"
some command ' file2
now it getline read from filename
if getline < "-"
some command' file2
now it read from file2
it doesn't mean that it read from stdin

Hey just take a try getline name < "-" you will know it will work for file processing.

Actually "sed & awk" had several examples of getline < "-" to read user's input from stdin.

I just want to know how to make it work for pipe.

Did you try:

Code:

command | getline

See vidyadhar85's post above.

You're right, getline < "-" gets the input from standard input.
What you can't do is to get input from a pipe and a file simultaneously. Get the users input in the BEGIN{} part.

Regards