Check if file exists, create new file?

Shell Programming and Scripting
1

Hi everyone, I'm brand new to shell scripts (and UNIX in general) and I've been able to figure everything out except this...

I want to write a script that will take a filename as an argument, append the date to it (IE Dec 24 2008) and make sure it doesn't already exist, if so, add an integer to the filename. So for example:

file0_Dec_24_2008
file1_Dec_24_2008 etc

This is what I have so far, but it keeps going into an endless loop I think because the script never finishes =\

#!/bin/bash
FILE=$1
X=$2
set $(date)
if [ ! -e "$FILE""$X"_$2_$3_$6 ]
then
touch "$FILE""$X"_$2_$3_$6
else
X=(( $X + 1 ))
bash filename1 $FILE $X
fi

so theoretically it should check to see if the file exists, and if not, create it. If it does, then it would recursively run the script again with the X increased by one. What am I missing??

2

Try a while loop instead.

#!/bin/bash
FILE=$1
X=$2
set $(date)
CREATED=FALSE
while [[ $CREATED == FALSE ]]; do
  if ! [ -e "$FILE""$X"_$2_$3_$6 ]; then
    touch "$FILE""$X"_$2_$3_$6
    CREATED=TRUE
  else
    X=(( $X + 1 ))
  fi
done
fi

I'm I ksh guy, and I'm taking for granted that the rest of your script works.

3

Padow, thanks so much for replying but I actually JUST figure it out shortly after I posted..

I messed up the part where I add one to the X variable, it should be this:
X=$(( X + 1 ))

The script works now! It starts with file_Dec_24_2008 and adds one to the filename from there.

The problem though is it's creating a LOT of processes...like over a hundred...is that normal?

4

I'd take out the part where you call your own program, replace that with a loop and see if that still occurs. With the way it is written now, you will have one copy of the script running for each version of the file that already exists.

5

Thanks again Padow I'll try that

EDIT: Using a while loop instead of that recursive script worked great, I just put it in the "else" part so that it would generate an unused filename followed by a touch to create it.

Writing scripts is fun =)