Well...anytime i tried to create a if else statements or either an else statement I get a message saying that the directory exists (mkdir: cannot create directory `./MAY2010': File exists
). I am running this in a crontab file and I dont want any output telling me that the directory exists. I just want to check if the directory doesnt exist, create one else do nothing (not even a message telling me that the directory exists).

Here is what I tried:
1. First try:

if [ -d $DIR ] ; then
echo " " #NOW I WANT TO GET RID OF THIS LINE AND SIMPLY
#DO NOTHING BUT I CANT just dont put nothign, it
#gives em some error when
#running the bash.
else
mkdir $DIR
fi



2nd try:

if ! [ -d $DIR ]; then
mkdir $DIR
fi

#Still tells me that the directory is created as output:
mkdir: cannot create directory `./MAY2010': File exists


3rd try:

if [ ! -d $DIR]; then
mkdir $DIR
fi

#Still the same message.

Any suggestions?
thanks!

maybe you should try exit..
or command false (that does nothing)

however your 1st try did't gave me any error

Try using double brackets:

1 members found this post helpful.

Your third try is the proper syntax. Try quoting your variable

yooy is does not give me an error but it outputs whatever the echo shows... and again output: (mkdir: cannot create directory `./MAY2010': File exists
), which I dont want.

grail and sploot, none of your suggestions gets rid of the output:

mkdir: cannot create directory `./MAY2010': File exists



:S

Thanks for all your help!

try "false" as zero output command

Use mkdir -p instead. It does not complain if directory already exists.

colucix thats what I was looking for ! Thanks again to all

Well color me confused??
Firstly I am curious why you would want to create a directory if one already existed (or a file of the same name as implied by error message)?
Second, does this mean the test is inaccurate? (ie the if says only try to mkdir if directory does not exist or is the issue that also a test for file needs to be included)?

btw. not having a shot at you Drigo ... just curious

I like this one most:

thanks Grail!

-m

That syntax has always worked without issue for me. I use it all the time.
Are you sure you don't have a file called MAY2010 there? The if will return false since the -d only tests for a directory of that name, and the mkdir will fail with that message since there's already a file with that name there.

Please use [code][/code] tags around your code and data, to preserve formatting and to improve readability. Please do not use quote tags, colors, or other fancy formatting.


Actually, all of the attempts posted in the OP should work just fine, provided the correct syntax is used (and there are no other file/directory conflicts, as discussed).


In the first example, we simply use any sub-command that does nothing on a successful match. The "true" placeholder command (":" is a synonym for it) is usually the recommended option. "false" can be used as well, but it might have a different effect if any subsequent command depends on reading the exit status of it. Even something like "echo -n" would do.

The second one works because placing a "!" in front of any command inverts the success/failure exit status of it. In this case you're reversing the status of the "test" command.

The third one is probably best though, as "!" is also the test command syntax for reversing the status of that individual match.


The important thing about all of them though is to remember that "test/[" is a command, just like any other, and so it's important to include spaces around each argument that comes after it. You also have to quote any variables and command substitutions, so that the expanded value doesn't get split into separate arguments from word-splitting and glob expansion.


See the Bash Pitfalls for details on common problems like this.
(I believe #4 is the main one, but for some reason the site currently isn't responding for me.)


As mentioned though, when using bash or ksh, it's usually recommended to use [[..]] for string/file tests. Since "[[" is a shell keyword, not a command, the shell can parse the line more safely, and doesn't do any word-splitting or expansion of variable contents.

In addition, when doing integer comparisons, you should use the ((..)) arithmetic evaluation brackets instead. In either case, avoid using the old [..] test unless you specifically need POSIX-style portability.

http://mywiki.wooledge.org/ArithmeticExpression
http://mywiki.wooledge.org/BashFAQ/031
http://wiki.bash-hackers.org/commands/classictest
http://wiki.bash-hackers.org/syntax/...nal_expression


And to give one final bit of advice, environment variables are generally all upper-case. So while not absolutely necessary, it's good practice to keep your own user variables in lower-case or mixed-case, to help differentiate them.

try [[ -d "$DIR/." ]]