Passing ksh variables into awk

[MHThomas]

Hi,
hopefully this is a quick and easy problem; I want to pass a variable into an awk script so I can select the Nth field in a one record file. Basically I need somebody to fix the syntax of the following example, or tell me I'm barking up the wrong tree...

#!/bin/ksh
n=10
cat /tmp/test.file | awk '{print $n}'

Cheers,

MarkT.

 

[dickiebird]

You're close - but the variable needs to be passed to awk
#!/bin/ksh
n=10
awk -v TMP="$n" '{print $TMP}' /tmp/test.file

No need for cat (UUOC)
HTH

Dickie Bird (-)))

 

[MHThomas]

Thanks for the quick response DB,
Works perfectly (of course).
Thanks for the heads-up on the UUOC, I'm new to scripting and am still a bit clunkie.

Cheers,

Mark T.

 

[jwernicki]

Believe it or not - the following works as well . .

#!/bin/ksh
n=10
cat silly.in |awk '{print $'"$n"'}'

Enclosing a ksh var in '" "' seems to do the trick. This way you're not forced into using all of awks clumsy syntax.

 

[MHThomas]

Thanks, it looks stupid, but it works great...

Cheers,

Mark T.

 

[dickiebird]

That's surprising ( and very handy ) !
Cheers Dickie Bird (-)))

 

[suchupramod]

Hi
I am using bourne shell and awk embedded in a shell script. I have been trying to use the trick of parameter passing to the awk, but it does not seem to work. Anyone has any idea?

What I did was:
#!/bin/bash
data="some_value"
awk -v var="$data"
'{print $var}'

The output says the {print $var}:command not found

 

[dickiebird]

Just use :
'{print var}'

The variable is known to awk as var, not $var



Dickie Bird (-)))

 

[suchupramod]

Thanks DB,

I used the same as you suggested i.e; used '{print var}' instead of '{print $var}', but says the same thing.

Any other idea

Sucheta

 

[dickiebird]

I created this :
#!/bin/bsh
data="some_value"
awk -v var="$data" '{print var}' db2

db2 is an small text file of two lines
result :
some_value
some_value

NB #!/bin/bsh
awk evaluates each line and does what it's told - to print var.
HTH


Dickie Bird (-)))

 

[suchupramod]

Hi,
is the output from awk '{printf var}' always redirected to a file.
In this case when I exactly replicated your code, it says can't open db2 for reading or writing(This file was not there before). When I created a file called as db2, it does not throw any error, but still returns an empty db2 file.

What you say?

Sucheta

 

[dickiebird]

Nowhere have you mentioned any redirection
To get output to another file do :
#!/bin/bsh
data="some_value"
awk -v var="$data" '{print var}' db2 > db3



Dickie Bird (-)))

 

[suchupramod]

Hi,
I am new to system administration stuff. I just wanted to store some files in the FTP sites of the server. My question is how do I do that, and where the files are actually stored.

Thanks in advance

Sucheta