Bash scripting and trying to determine whether a directory exists?

obelxi · 03-18-2005, 08:58 PM

Hi All,

I was wondering if someone could help me figure out how to write a bash script that will determine whether or not a directory exists.

#!/bin/bash

DIR=/home/optio/test/

if [ "`ls $DIR > /dev/null 2>&1 | wc -l | awk '{print $1}']; then
echo "do not create $DIR"

else
echo "create $DIR"
fi

My friend gave me that as an example a while ago, but it just doesn't make any sense to me and when I run it, the command fails. I am wondering if someone could explain how I could fix this script, and more importantly how it works. I know that all shell commands can be written to stdout but the art of processing this information is lost to me. Any help would be greatly appreciated.

homey · 03-18-2005, 09:21 PM

How about something like this...

Code:

#!/bin/bash

dir=/home/optio/test/

if [ -d $dir ] ; then
   echo "do not create $dir"
else
   echo "create $dir"
fi

obelxi · 03-18-2005, 09:35 PM

Yes that makes a lot more sense to me than the nasty awk and wc commands. I've got one more question. How do you nest an if/else statement within an if/elif chain....

Here's what this question is a larger part of. I want to nest that if/else within the elif but it keeps giving me the error:

unexpected EOF while looking for matching `"'
syntax error: unexpected end of file

And then the line number that corresponds to the line just after the end of the else statement. It doesn't matter if I put a fi in there or not it still produces the same result.

#!/bin/sh

filename=$1
MACHINE_TYPE=`uname -s`
if [ "$MACHINE_TYPE" == "Darwin" ]; then
echo "Yay, you're running a Macintosh"
elif [ "$MACHINE_TYPE" == "Linux" ]; then
echo "Yay, you're running a Linux box"
dir=/tmp/pov-Script

if [ -d $dir ] ; then
echo "do not create $dir"
else
echo "create $dir"
mkdir /tmp/pov-script
chmod 777 /tmp/pov-script
fi

cd /tmp/pov-script
pwd
curl -O http://obelix.ca/xgrid/$filename".pov"
sleep 1
/opt/local/bin/povray $filename".pov" +W640 +H480
ls -la
curl -T $filename".png" -u user

ass -O \
ftp://obelix.ca/public_html/xgrid/$filename".png"
echo "Finished rendering scripts, they are available on the server"
fi

homey · 03-18-2005, 10:13 PM

That's strange. I put an echo statement just before curl like this...

Code:

echo "you made it this far"
#curl -O http://obelix.ca/xgrid/$filename".pov"
#sleep 1
#/opt/local/bin/povray $filename".pov" +W640 +H480
#ls -la
#curl -T $filename".png" -u user:pass -O \
#ftp://obelix.ca/public_html/xgrid/$filename".png"
#echo "Finished rendering scripts, they are available on the server"
fi

and here is the output....

Code:

# ./test file.txt
Yay, you're running a Linux box
do not create /tmp/pov-script
/tmp/pov-script
you made it this far

Edit: Maybe you should change the filename parts to this....
"$filename.pov"
and
"$filename.png"

obelxi · 03-18-2005, 10:20 PM

so there isn't anything inherently wrong in my code then?

homey · 03-18-2005, 10:24 PM

On second thought, try it without quotes at all...
$filename.pov
and
$filename.png

obelxi · 03-19-2005, 12:42 AM

I don't know what I did but I added some quotes onto a line and it works flawlessly now. Excellent. Thanks for your help.

Dave Kelly · 03-19-2005, 05:37 PM

Quote:

Originally posted by obelxi
I don't know what I did but I added some quotes onto a line and it works flawlessly now. Excellent. Thanks for your help.

Can you post a list of the files you were trying to read and we'll see why you got an error and why quotation marks solved your problem.

izza_azhar · 04-15-2005, 05:59 AM

its work..thanks

purefan · 04-18-2005, 11:22 PM

hello
where can I find a tutorial on scripts creation?
I understand that I must write the commands I would execute in bash but I don't know with what extension the file should be saved, or if it needs to be run in some program.
I read about the script program but Im not sure how to use it...