I would like to know how can we find the end of file when reading from
a file using shell script.

Basically, I want to read 2 lines using a while loop till it reaches
the end of a file. Here is how I am reading 2 lines from the
result-data file inside a while loop.

do
{
read line1
read line2
} < result-data
done

Can anyone let me know how can I check for the end of file from a shell
script.

Thanks,
Sekar

2006-11-7, 11:38(-08), doni:
> I would like to know how can we find the end of file when reading from
> a file using shell script.
>
> Basically, I want to read 2 lines using a while loop till it reaches
> the end of a file. Here is how I am reading 2 lines from the
> result-data file inside a while loop.
>
> do
> {
> read line1
> read line2
> } < result-data
> done
[...]

while
IFS= read -r line1 <&3 &&
IFS= read -r line2 <&3
do
...
done 3< result-data

read without "-r" and/or if $IFS contains any blank character
has a very special meaning to the shell, you should not do that
unless you know what you're doing and why. That's one of the
dodgy designs of shells. Using file descriptor 3 instead of 0
s in case you want to get something from the user within the
loop.

It should be noted that if the end of line is reached after
line1 is read but before line2 is read, the loop will stop
without processing the $line1 just read.

--
Stéphane

On 2006-11-07, doni wrote:
> I would like to know how can we find the end of file when reading from
> a file using shell script.
>
> Basically, I want to read 2 lines using a while loop till it reaches
> the end of a file. Here is how I am reading 2 lines from the
> result-data file inside a while loop.
>
> do
> {
> read line1
> read line2
> } < result-data
> done
>
> Can anyone let me know how can I check for the end of file from a shell
> script.

while read line1; read line2
do
# Do whatever you want here, e.g.:
printf "%s %s\n" "$line1" "$line2"
done < result-data


Depending on the input, you may want to use:

while IFS= read -r line1; IFS= read -r line2

--
Chris F.A. Johnson, author <http://cfaj.freeshell.org/shell>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

Thanks Chris and Stephane.

Sekar


Chris F.A. Johnson wrote:
> On 2006-11-07, doni wrote:
> > I would like to know how can we find the end of file when reading from
> > a file using shell script.
> >
> > Basically, I want to read 2 lines using a while loop till it reaches
> > the end of a file. Here is how I am reading 2 lines from the
> > result-data file inside a while loop.
> >
> > do
> > {
> > read line1
> > read line2
> > } < result-data
> > done
> >
> > Can anyone let me know how can I check for the end of file from a shell
> > script.
>
> while read line1; read line2
> do
> # Do whatever you want here, e.g.:
> printf "%s %s\n" "$line1" "$line2"
> done < result-data
>
>
> Depending on the input, you may want to use:
>
> while IFS= read -r line1; IFS= read -r line2
>
> --
> Chris F.A. Johnson, author <http://cfaj.freeshell.org/shell>
> Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
> ===== My code in this post, if any, assumes the POSIX locale
> ===== and is released under the GNU General Public Licence