How to create a temporary directory?

Question

I use to create a tempfile, delete it and recreate it as a directory:

temp=`tempfile`
rm -f $temp
  # <breakpoint>
mkdir $temp

The problem is, when it runs to the <breakpoint>, there happens to be another program wants to do the same thing, which mkdir-ed a temp dir with the same name, will cause the failure of this program.

Answer 1

Use mktemp -d. It creates a temporary directory with a random name and makes sure that file doesn't already exist. You need to remember to delete the directory after using it though.

Answer 2

For a more robust solution i use something like the following. That way the temp dir will always be deleted after the script exits.

The cleanup function is executed on the EXIT signal. That guarantees that the cleanup function is always called, even if the script aborts somewhere.

#!/bin/bash    

# the directory of the script
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

# the temp directory used, within $DIR
# omit the -p parameter to create a temporal directory in the default location
WORK_DIR=`mktemp -d -p "$DIR"`

# check if tmp dir was created
if [[ ! "$WORK_DIR" || ! -d "$WORK_DIR" ]]; then
  echo "Could not create temp dir"
  exit 1
fi

# deletes the temp directory
function cleanup {      
  rm -rf "$WORK_DIR"
  echo "Deleted temp working directory $WORK_DIR"
}

# register the cleanup function to be called on the EXIT signal
trap cleanup EXIT

# implementation of script starts here
...

Directory of bash script from here.

Bash traps.

Answer 3

My favorite one-liner for this is

cd $(mktemp -d)

Answer 4

The following snippet will safely create and then clean up a temporary directory.

The first trap line executes exit 1 command when any of the specified signals is received. The second trap line removes the $TEMPD on program's exit (both normal and abnormal). We initialize these traps after we check that mkdir -d succeeded to avoid accidentally executing the exit trap with $TEMPD in an unknown state.

#!/bin/bash

# set -x # un-comment to see what's going on when you run the script

# Create a temporary directory and store its name in a variable.
TEMPD=$(mktemp -d)

# Exit if the temp directory wasn't created successfully.
if [ ! -e "$TEMPD" ]; then
    >&2 echo "Failed to create temp directory"
    exit 1
fi

# Make sure the temp directory gets removed on script exit.
trap "exit 1"           HUP INT PIPE QUIT TERM
trap 'rm -rf "$TEMPD"'  EXIT

Answer 5

Here is a simple explanation about how to create a temp dir using templates.

1. Creates a temporary file or directory, safely, and prints its name.
2. TEMPLATE must contain at least 3 consecutive 'X's in last component.
3. If TEMPLATE is not specified, it will use tmp.XXXXXXXXXX
4. directories created are u+rwx, minus umask restrictions.

PARENT_DIR=./temp_dirs # (optional) specify a dir for your tempdirs
mkdir $PARENT_DIR

TEMPLATE_PREFIX='tmp' # prefix of your new tempdir template
TEMPLATE_RANDOM='XXXX' # Increase the Xs for more random characters
TEMPLATE=${PARENT_DIR}/${TEMPLATE_PREFIX}.${TEMPLATE_RANDOM}

# create the tempdir using your custom $TEMPLATE, which may include
# a path such as a parent dir, and assign the new path to a var
NEW_TEMP_DIR_PATH=$(mktemp -d $TEMPLATE)
echo $NEW_TEMP_DIR_PATH

# create the tempdir in parent dir, using default template
# 'tmp.XXXXXXXXXX' and assign the new path to a var
NEW_TEMP_DIR_PATH=$(mktemp -p $PARENT_DIR)
echo $NEW_TEMP_DIR_PATH

# create a tempdir in your systems default tmp path e.g. /tmp 
# using the default template 'tmp.XXXXXXXXXX' and assign path to var
NEW_TEMP_DIR_PATH=$(mktemp -d)
echo $NEW_TEMP_DIR_PATH

# Do whatever you want with your generated temp dir and var holding its path

Answer 6

I need the following features:

• Put all temp files into a single directory with a specific namespace for reusing.
• Create temp files with filename prefix and suffix (extension).

With bash script on macOS:

$ namespace="com.namespace.mktemp"

# find directory for reusing
$ ls -d "${TMPDIR}${namespace}"*

# create directory if not exists
$ mktemp -d -t "$namespace"
/var/folders/s_/.../T/com.namespace.mktemp.HjqGT6w2

# create tempfile with directory name and file prefix
$ mktemp -t "com.namespace.mktemp.HjqGT6w2/file-prefix"
/var/folders/s_/.../T/com.namespace.mktemp.HjqGT6w2/file-prefix.sZDvjo14

# add suffix - `mktemp` on macOS does not support `--suffix`
mv "/var/folders/s_/.../file-prefix.sZDvjo14" "/var/folders/s_/.../file-prefix.sZDvjo14.txt"

The gmktemp (brew install coreutils) is a little different:

• supports --suffix and --tmpdir
• Xs are required in template and prefix
• template should not contain directory, set TMPDIR instead

$ namespace="com.namespace.gmktemp"

# create directory if not exists
$ gmktemp -d -t "$namespace.XXXXXXXX"
/var/folders/s_/.../T/com.namespace.gmktemp.BjFtIAyZ

# set TMPDIR
TMPDIR="/var/folders/s_/.../T/com.namespace.gmktemp.BjFtIAyZ"

# create tempfile with directory name and file prefix
$ gmktemp --suffix=".txt" -t "prefix.XXXXXXXX"
/var/folders/s_/.../T/com.namespace.gmktemp.BjFtIAyZ/prefix.LWHj0G95.txt