Hey all,

I have a script (using ksh88) that takes in STDIN and stores it within
a variable.

Is it more apropriate to use 'cat' to do this ala:

FOO=$(cat)

or is it acceptabe (prefered) to do it this way:

FOO=$(</dev/fd/0)

This is how I am doing it now but am I setting my self up for trouble
in the future?

Thanks
--Brett

On 22 Aug 2006 07:16:08 -0700, mr.bmonroe@gmail.com
<mr.bmonroe@gmail.com> wrote:
> Hey all,
>
> I have a script (using ksh88) that takes in STDIN and stores it within
> a variable.
>
> Is it more apropriate to use 'cat' to do this ala:
>
> FOO=$(cat)
>
> or is it acceptabe (prefered) to do it this way:
>
> FOO=$(</dev/fd/0)
>
> This is how I am doing it now but am I setting my self up for trouble
> in the future?
>
The usual way is "read FOO", unless you want FOO to contain more than
one line. If that is the case, remind the user to press ctrl-D at the
end.


--
We must die because we have known them.
-- Ptah-hotep, 2000 B.C.

Bill Marcum wrote:
> On 22 Aug 2006 07:16:08 -0700, mr.bmonroe@gmail.com
> <mr.bmonroe@gmail.com> wrote:
> > Hey all,
> >
> > I have a script (using ksh88) that takes in STDIN and stores it within
> > a variable.
> >
> > Is it more apropriate to use 'cat' to do this ala:
> >
> > FOO=$(cat)
> >
> > or is it acceptabe (prefered) to do it this way:
> >
> > FOO=$(</dev/fd/0)
> >
> > This is how I am doing it now but am I setting my self up for trouble
> > in the future?
> >
> The usual way is "read FOO", unless you want FOO to contain more than
> one line. If that is the case, remind the user to press ctrl-D at the
> end.

Bill,

Two things (sorry I didn't mension them in my first email):

First, the script is not interactive, it is called by a 3rd party
program that spews a report to STDOUT.

Second, the output is multilined and can be anywhere from 10 to 50+
lines long. I want to map the text to a variable so as to avoid
parsing a temp file over and over (with the rest of the script). The
parsing is simple so I am using expr for the most part.

Thanks
--Brett

On 22 Aug 2006 07:16:08 -0700, mr.bmonroe@gmail.com wrote:
> Hey all,
>
> I have a script (using ksh88) that takes in STDIN and stores it within
> a variable.
>
> Is it more apropriate to use 'cat' to do this ala:
>
> FOO=$(cat)
>
> or is it acceptabe (prefered) to do it this way:
>
> FOO=$(</dev/fd/0)
>
> This is how I am doing it now but am I setting my self up for trouble
> in the future?
[...]

FOO=$(cat)

is the correct way. $(<...) is shell dependant and /dev/fd/0 is
not available on all systems.

Please note that will both approaches, all the trailing newline
characters in stdin will be trimmed.

Use

FOO=$(cat; echo .); FOO=${FOO%.}

to work around it.

Another way to do it, less legible but may be faster for small
files:

FOO=
NL='
'
while IFS= read -r line; do
FOO=$FOO$line$NL
done
FOO=$FOO$line

In every case, remember that the NUL character can not be stores
in a shell variable, so you can't process binary files that way.

--
Stephane