I am writing a shell script to run under the KornShell (ksh) on AIX. I would like to use the mkdir command to create a directory. But the directory may already exist, in which case I do not want to do anything. So I want to either test to see that the directory does not exist, or suppress the "File exists" error that mkdir throws when it tries to create an existing directory.
How can I best do this?
Try mkdir -p:
mkdir -p foo
Note that this will also create any intermediate directories that don't exist; for instance,
mkdir -p foo/bar/baz
will create directories foo, foo/bar, and foo/bar/baz if they don't exist.
Some implementation like GNU mkdir include mkdir --parents as a more readable alias, but this is not specified in POSIX/Single Unix Specification and not available on many common platforms like macOS, various BSDs, and various commercial Unixes, so it should be avoided.
If you want an error when parent directories don't exist, and want to create the directory if it doesn't exist, then you can test for the existence of the directory first:
[ -d foo ] || mkdir foo
mkdir on Unix-like systems, not on Windows. -p is required for POSIX/Single Unix Specification compliance, so anything that intents to comply with those specifications will support -p. Windows is entirely different, unless you use a POSIX emulation layer like Cygwin or MSYS. –
Gowon mkdir -p, you can use brackets! {} to create "complex" directory tree in a command. See here: technosophos.com/2010/04/15/… –
Say || instead of && because then the whole line has the right exit status. Important if your shell runs with errexit or if that line is the last one in a function, switch-case, whatever. –
Mantelpiece mkdir somedir 2>/dev/null || true –
Blockbusting mkdir; the shell expands such an expression to a discrete list of argument that are passed to mkdir. –
Shaveling mkdir, in this case). So if you had directories a, b, and c, mkdir -p */foo/bar/baz would be the same as mkdir -p a/foo/bar/baz b/foo/bar/baz c/foo/bar/baz. mkdir can take multiple arguments, and when given -p, it will create needed intermediate directories. Experiment with this yourself. Try echo mkdir -p */foo/bar/baz to see what command is run; or just try running it in a test directory. –
Gowon touch {a,b,c}.txt –
Conga [ -d foo ] || mkdir foo. 🤗 –
Spongin This should work:
$ mkdir -p dir
or:
if [[ ! -e $dir ]]; then
mkdir $dir
elif [[ ! -d $dir ]]; then
echo "$dir already exists but is not a directory" 1>&2
fi
which will create the directory if it doesn't exist, but warn you if the name of the directory you're trying to create is already in use by something other than a directory.
Use the -p flag.
man mkdir
mkdir -p foo
Defining complex directory trees with one command
mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}
mkdir itself, but the shell that executes the command. It's called brace expansion - AFAIK, only Bash, ksh, zsh, and the C shell support it. –
Whipcord folder name you need to use folder\ name) –
Lancers If you don't want to show any error message:
[ -d newdir ] || mkdir newdir
If you want to show your own error message:
[ -d newdir ] && echo "Directory Exists" || mkdir newdir
mkdir -p if you do not want race conditions. But you won't get to show your own Directory exists error. –
Retract mkdir foo works even if the directory exists.
To make it work only if the directory named "foo" does not exist, try using the -p flag.
Example:
mkdir -p foo
This will create the directory named "foo" only if it does not exist. :)
You can either use an if statement to check if the directory exists or not. If it does not exits, then create the directory.
dir=/home/dir_name
if [ ! -d $dir ]
then
mkdir $dir
else
echo "Directory exists"
fi
You can directory use mkdir with -p option to create a directory. It will check if the directory is not available it will.
mkdir -p $dir
mkdir -p also allows to create the tree structure of the directory. If you want to create the parent and child directories using same command, can opt mkdir -p
mkdir -p /home/parent_dir /home/parent_dir/child1 /home/parent_dir/child2
Simple, silent and deadly:
mkdir -p /my/new/dir >/dev/null 2>&1
mkdir -p my/new/dir does not complain if my/new/dir already exists, no need to redirect output –
Hopehopeful -p still fails on windows when the folder exists –
Evapotranspiration mkdir -p /parent/dir complain if permissions prevent creating /parent/dir ? If so, perhaps the redirection might be considered "deadly" or at least unwise. –
Xerophilous The old tried and true
mkdir /tmp/qq >/dev/null 2>&1
will do what you want with none of the race conditions many of the other solutions have.
Sometimes the simplest (and ugliest) solutions are the best.
[ -d newdir ] || mkdir newdir, where the directory does not initially exist, has a race condition in that, between the test for existence and the attempted creation, another process could swoop in and create the directory. Hence the mkdir would then fail. –
Waterrepellent /tmp has likely been chosen in the example to represent a base-path that always exists and is write-able to the current user, e.g. the user has enough rights to create a directory in. You raise a valid point thought:: the logic is a bit contradictory, as when this command fails, it can mean two things: 1.) the directory exists or 2.) the directory could not be created. This is not true for the operation itself, therefore a simple post-check on the directory path can give the confirmation, or the next command that operates on. –
Juggler mkdir -p /tmp/qq > /dev/null 2>&1 will create /tmp/ if missing. –
Mayence mkdir does not support -p switch anymore on Windows 8+ systems.
You can use this:
IF NOT EXIST dir_name MKDIR dir_name
directory_name = "foo"
if [ -d $directory_name ]
then
echo "Directory already exists"
else
mkdir $directory_name
fi
This is a simple function (Bash shell) which lets you create a directory if it doesn't exist.
#------------------------------------------#
# Create a directory if it does not exist. #
#------------------------------------------#
# Note the "-p" option in the mkdir #
# command which creates directories #
# recursively. #
#------------------------------------------#
createDirectory() {
mkdir -p -- "$1"
}
You can call the above function as:
createDirectory "$(mktemp -d dir-example.XXXXX)/fooDir/BarDir"
The above creates fooDir and BarDir if they don't exist. Note the "-p" option in the mkdir command which creates directories recursively.
Or if you want to check for existence first:
if [[ ! -e /path/to/newdir ]]; then
mkdir /path/to/newdir
fi
-e is the exist test for KornShell.
You can also try googling a KornShell manual.
Referring to man page man mkdir for option -p
-p, --parents
no error if existing, make parent directories as needed
which will create all directories in a given path, if exists throws no error otherwise it creates all directories from left to right in the given path. Try the below command. the directories newdir and anotherdir doesn't exists before issuing this command
Correct Usage
mkdir -p /tmp/newdir/anotherdir
After executing the command you can see newdir and anotherdir created under /tmp. You can issue this command as many times you want, the command always have exit(0). Due to this reason most people use this command in shell scripts before using those actual paths.
Improvement on the 'classic' solution (by Brian Campbell) - to handle the case of symlink to a directory.
[ -d foo/. ] || mkdir foo
mkdir -p sam
if [ !-d $dirName ];then
if ! mkdir $dirName; then # Shorter version. Shell will complain if you put braces here though
echo "Can't make dir: $dirName"
fi
fi
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