Extracting the 4th word of the first line in a file - is there a more elegant solution?

Extracting the 4th word of the first line in a file - is there a more elegant solution?

[Ronald Fischer]

Within a script, I have need to store the 4th word in the first line of
a file.

Of course this is trivial to implement. However, I'm curious whether
there exists a better way to implement than what I found.

My current solution goes like this:

# $1 is the filename
line=$(head -n 1 $1)
field=${lin[(w)4]}

This is OK, but this needs an auxiliary variable 'line'. 


I could also do it like this:

field=$(head -n 1 $1|cut  -f 4 -d ' ')

No aux variable, but needs a pipe


So I wonder, whether there is a elegant "zsh" solution, which solves
this in a more elegant way?

Ronald
-- 
Ronald Fischer <ronaldf@eml.cc>
+  If a packet hits a pocket on a socket on a port, 
+  and the bus is interrupted and the interrupt's not caught,
+  then the socket packet pocket has an error to report.
+		(cited after Peter van der Linden)

Re: Extracting the 4th word of the first line in a file - is there a more elegant solution?

[Peter Stephenson]

On Fri, 18 May 2012 15:16:54 +0200
Ronald Fischer <ynnor@mm.st> wrote:
> # $1 is the filename
> line=$(head -n 1 $1)
> field=${lin[(w)4]}

It depends a bit how big the file is.  If it's small, it's very easy,
and involves no extra processes (the "$(<...)" is optimised to a read):

  field=${$(<$1)[4]}

The disadvantage is that reads the entire file into memory first.  It's
hard to think of a way that avoids that that doesn't use an auxiliary
process, but apart from that it's still relatively straightforward
within zsh:

  field=${$(read -e <$1)[4]}

This reads a single line from the file and echoes it instead of
assigning it to a parameter.  You might want "read -qe" if the file
contains backslashes.

You can do it without an auxiliary process, but with a local variable,
which is probably more efficient and the best compromise:

  read -A line <$1
  field=$line[4]

-- 
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Re: Extracting the 4th word of the first line in a file - is there a more elegant solution?

[Bart Schaefer]

On May 18,  2:30pm, Peter Stephenson wrote:
}
} You can do it without an auxiliary process, but with a local variable,
} which is probably more efficient and the best compromise:
} 
}   read -A line <$1
}   field=$line[4]

If you're already using a local throwaway,

    read x x x field x <$1

Or you can use the omnipresent local argv so you needn't declare it:

    (){ read -A argv; field=$4 } < $1

} You might want "read -qe" if the file contains backslashes.

I believe -q is a typo for -r there.