Question

(simple) compare a string with EOF

Asked by: sunilvirus

i am new to shell programming.

the situation is like this...
i read a command from the console,and store it in a variable.
i did it using "read var".

now the problem is...
how can i detect if it is EOF.
this is necessary because, some file may be redirected to my program.

i tried with some thing like...
if ($var = EOF)
etc. but no use.
please help me.

thanks in advance.

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Asked On
2002-08-05 at 00:11:35ID20332833
Tags

string

,

compare

,

read

Topic

Linux Programming

Participating Experts
2
Points
50
Comments
11

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Answers

 

by: sunilvirusPosted on 2002-08-05 at 00:14:15ID: 7200280

i also tried using...
if ( $var )
but not working

 

by: ahoffmannPosted on 2002-08-05 at 02:27:54ID: 7200472

while read var; do
  echo "Var=$var"
done

 

by: MikeOM_DBAPosted on 2002-08-05 at 11:03:18ID: 7201511

Try this:

while read var; do
  if [ "$var" == '' ]
  then
    echo "Var=EOF!"
    exit
  else
    echo "Var=$var"
  fi
done

 

by: ahoffmannPosted on 2002-08-05 at 12:09:47ID: 7201628

> if [ "$var" == '' ]; then
matches for emty line too, not only EOF

 

by: MikeOM_DBAPosted on 2002-08-05 at 12:57:40ID: 7201731

Ok, the try this:

eof=0
while read var; do
  if [ "$var" == '' ]
  then
    eof=1
    echo "Var is empty."
    break
  else
    echo "Var=$var"
  fi
done
if [ $eof -eq 0 ]
then
  echo 'control-d pressed.'
fi

 

by: ahoffmannPosted on 2002-08-05 at 13:04:12ID: 7201743

just a bit more complicated than that what I already suggested ;-)

 

by: sunilvirusPosted on 2002-08-07 at 04:55:42ID: 7205649

i want it in the 'if condition'

 

by: ahoffmannPosted on 2002-08-07 at 05:33:49ID: 7205736

> i want it in the 'if condition'
Why?
The end of the while loop is exactly your if condition.

 

by: MikeOM_DBAPosted on 2002-08-07 at 09:09:07ID: 7206414

What ahoffman means is that when an end-of-file (EOF) is reached (or control-d pressed to generate an EOF), the statements inside the while loop are no longer executed. therefore you cannot test for EOF inside the while loop.
His short solution is the correct one, mine was only an example of how to break the loop when a null (CR) is read.

 

by: sunilvirusPosted on 2002-08-07 at 09:30:57ID: 7206491

congrats to ahoffmann.

you will get the points.
i solved my problem.

initially i was not able to solve my problem because of a small typo error. i typed...

while read var do
....
done

i skipped the semi-color(;)


any how thanks to all.

 

by: ahoffmannPosted on 2002-08-07 at 14:14:57ID: 7207053

KISS - keep it small and simple
Hope you all get used to the EOF inside scripts now ^-)

20120131-EE-VQP-002

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