Shell Programming and Scripting

Dear all,

Im trying to use awk with read commands.

I want to print the line if the first field equal the input using read command

my code..

read A

awk {if ($1==A) {print $0}} file

still the output is nothing...

any clue

Sorry, the code is

read A

awk {if ($1==$A) {print $0}} file

Code:

read A

awk -v var="$A" 'var==$1' file

Regards

Thank you very much.. but can you tell me what was wrong with my code, and could you tell me what is -v used for ?

Thank you again

That's a way to use shell variables in awk. You can also do something like:

Code:

awk '$1 ~ '"$A" file

If you don't place single quotes around the awk command, the shell tries to expand all the variables prefixed by a "$". Above the variable $A is not within the single quotes because it must expand by the shell.

Regards

Well, it doesn't works because AWK doesn't know shell variables. You have to pass a variable to AWK and one way how to do that is as Franklin wrote. Another way is:

read A # let's say we input "hello"
awk '{if ($1=="'$A'") {print $0}}' file # so that after parsing of the line by shell and before the awk is run the line will look like: awk '{if ($1=="hello") {print $0}}' file

======================================
from my GAWK man page:

-v var=val
--assign var=val
Assign the value val to the variable var, before execution of
the program begins. Such variable values are available to the
BEGIN block of an AWK program.

Thank you both... you helped me a lot...
Best regards