Checking the existence of a file.. - Shell Programming and Scripting

igandu · #1 (**permalink**) 06-12-2007

Hi,

I am trying to check for the existence of a file using the 'test' and the file existence options.
When trying to check for a file with a space in between e.g 'Team List', it gives the following error.

learn1: line 3: test: `Team: binary operator expected

I am pasting my code below as well:

echo "Please enter a file name"
read fname
if test -f $fname
then
echo "$fname exists"
else
echo "$fname doesnot exist"
fi

Can someone help me with this...

Regards,
Indra

gabe · #2 (**permalink**) 06-12-2007

Try using double quotes around your variable that holds the file name.

Code:

»if test -f "$filename"; then
©:echo "success"
©:else
©:echo "failure"
©:fi
success

igandu · #3 (**permalink**) 06-12-2007

Hi Gabe,

can you also explain how would the double quotes make the difference.

Regards,
Indra

Shell_Life · #4 (**permalink**) 06-12-2007

Indra,
Try using " (double quote) before and after $fname:

Code:

echo "Please enter a file name"
read fname
if test -f "$fname""
then
  echo "$fname exists"
else
  echo "$fname doesnot exist"
fi

solfreak · #5 (**permalink**) 06-12-2007

Space is one of the default input field seperators.
So, if you just use $fname then that's 2 arguments for test and hence doesn't work.
"$fname" is just 1 argument.

gabe · #6 (**permalink**) 06-12-2007

solfreak is on the money with this one.

If you consider that the test command is looking for a single argument, and then you provide it with a list, then it will only test the first item in that list.

So, I created a test script named "test.ksh". Here it is:

Code:

#! /usr/bin/ksh

echo "enter a file name: \c"
read filename

if test -f "${filename}"; then
   echo "Success: ${filename}"
   else
     echo "Failure: ${filename}"
fi

I also created a file in the same directory named "one two.txt".

Code:

»ls
one two.txt  test.ksh
»test.ksh 
enter a file name: one two.txt
Success: one two.txt

Then I changed test.ksh to remove the double quotes around the variable "filename":

Code:

#! /usr/bin/ksh

echo "enter a file name: \c"
read filename

if test -f ${filename}; then
   echo "Success: ${filename}"
   else
     echo "Failure: ${filename}"
fi

I ran this in an identical manner as before:

Code:

»test.ksh
enter a file name: one two.txt
Failure: one two.txt

I believe that this is due to the way that the test function works. When presented with a list of words separated by spaces, it tests the first item in that list (in this case, part of a filename), but if that list of words is surrounded by double quotes, then it is viewed as a single argument, and the test is then successful.

hth,
gabe

igandu · #7 (**permalink**) 06-13-2007

Thanks everyone for helping me with this.

Thanks & regards,
Indra

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