How to Generate UUID in Bash [3 Simple Methods]

UUID or Universal Unique Identifier is used to uniquely identify almost all the entities such as files, digital objects etc. There are many versions and variants of UUIDs. One can generate UUIDs based on different algorithms. In Bash, you can take various different approaches to generate UUID. This article discusses those techniques elaborately.

Key Takeaways

• Understanding about UUID.
• UUIDs version and variants.
• Techniques of generating UUIDs in Bash.

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What is UUID?

A UUID or Universally Unique Identifier is a 128-bit identifier that is almost guaranteed to be unique until the year 3400. It can identify almost anything imaginable on the internet including databases, Bluetooth devices and objects within a short lifetime. A UUID sequence of 32 hexadecimal digits is typically divided into five groups separated by hyphens, like below- 123e4567-e89b-12d3-a456-426655440000.

GUID in other words Global Unique Identifier is actually a variant of UUID used by Microsoft. UUIDs have a couple of variants and versions.

3 Ways of Getting UUID in Bash

There are multiple ways to generate UUID in Bash. One can use uuidgen command, system kernel or even python uuid module to generate UUID. I am going to discuss these techniques below.

Method 1: Using uuidgen Command to Generate UUID

The uuidgen command in Bash is super useful to generate UUID in Unix based system. It offers multiple options such as -r, -t and -n to generate UUIDs with different randomness based on various algorithms.

Case 1: Creating random-based UUIDs in Bash

By default the uuidgen command creates random-based UUID. However, one can deliberately use -random or -r option to generate random-based UUIDs. This provides high-quality randomness of the generated UUID.

Steps to Follow >

❶ At first, launch an Ubuntu Terminal.

❷ Write the following command to open a file named randomuuid.sh in the build-in nano editor:

nano randomuuid.sh

❸ Copy the following scripts and paste them into nano. Press CTRL+O and ENTER to save the file; CTRL+X to exit. Alternatively, copy the following script. Paste the script in a text editor and save it as .sh file.

Script (randomuuid.sh) >

#!/bin/bash

uuid=$(uuidgen -r)
echo "Generated Random-based UUID: $uuid"

❹ Use the following two commands to make both file executable:

chmod u+x randomuuid.sh

❺ Run the randomuuid.sh script by the following command:

./randomuuid.sh

When executed, the script generates a random based UUID as highlighted in the above image.

Case 2: Creating time-based UUID in Bash

Time-based UUIDs are useful when you need to associate a unique identifier with a specific point in time. -t option of the uuidgen command used to generate time-based UUIDs.

Script (timeuuid.sh) >

#!/bin/bash

uuid=$(uuidgen -t)
echo "Generated Time-based UUID: $uuid"

Run the timeuuid.sh script by the following command:

./timeuuid.sh

When executed, the program generates a time-based UUID as shown in the image.

Case 3: Creating hash-based UUID in Bash

One can use uuidgen command to generate UUIDs using cryptographic hash algorithms like MD5 or SHA1.

Script (hashuuid.sh) >

#!/bin/bash

echo "Generated UUID using hash algorithm: $(uuidgen -m -N www.linuxsimply.com -n @url)

Run the hashuuid.sh script by the following command:

./hashuuid.sh

Once executed the script creates a UUID as highlighted in the above image.

Another commonly used hash algorithm is SHA1 algorithm. To generate UUID using hash algorithm SHA1 one must enable the -s option of the uuidgen command. An example command can be like this-

uuidgen -s -N www.linuxsimply.com -n @url

Method 2: Using Kernel Random Generator to Generate UUID in Bash

One can use the system kernel to generate UUIDs. The /proc/sys/kernel/random/uuid file generates a UUID each time one tries to read the content of this file using a command such as cat. This approach uses the kernel random generator.

Script (kernel.sh) >

#!/bin/bash

echo "Random generated UUID: $(cat /proc/sys/kernel/random/uuid)"

Run the kerneluuid.sh script by the following command:

./kernel.sh

When executed, the program shows a kernel generated UUID as shown in the image.

Method 3: Using Python uuid Module in Bash

If your system has python installed in it then you can generate UUID using python uuid module. This module offers the uuid4() function that can generate random based  Universal Unique Idenfier.

Script (pythonuuid.sh) >

#!/bin/bash

uuid=$(python -c "import uuid; print(uuid.uuid4())")
echo "Python Generated UUID: $uuid"

Run the pythonuuid.sh script by the following command:

./pythonuuid.sh

When executed, the program shows UUID using the Python uuid module as shown in the image.

• If Python is not installed in your system, use the command below to install Python:

sudo apt install python-is-python3

• To generate time based UUIDs use uuid1() function as follows:

python –c "import uuid; print(uuid.uuid1())"

• One can create UUIDs using MD5 and SHA1 hash algorithms. To create hash-based UUIDs using MD5 algorithm use uuid3() function.

python -c "import uuid; print(uuid.uuid3(uuid.NAMESPACE_URL, 'www.linuxsimply.com'))"

Here, uuid.NAMESPACE_URL is the first argument of the function uuid3() that takes the namespace string to generate UUID.

• To generate hash-based UUID using SHA1, use the following command:

python -c "import uuid; print(uuid.uuid5())"

Comparative Analysis of Methods

Here is a comparative analysis between the above-discussed methods. Take a look at the analysis to determine which method suits your need.

From personal experience, I would suggest you to use the uuidgen command to generate UUID. This command is flexible and generates UUID with higher order randomness.

Comparing two UUIDs in Bash

UUIDs are expected to be highly unique, but two UUIDs can appear similar when you clone something. In the script below, I will create a Bash script that can compare two UUIDs to determine whether they are similar or not:

Script (compare.sh) >

#!/bin/bash

# Generate two UUIDs and store them in an array
uuids=()

for i in {1..2}; do
uuids+=("$(uuidgen)")
done

# Compare the two UUIDs
if [ "${uuids[0]}" = "${uuids[1]}" ]; then
echo "UUIDs are identical."
else
echo "UUIDs are different."
fi

Run the compare.sh script by the following command:

./compare.sh

Once executed the program shows that two UUIDs it generated within the code are not identical.

Conclusion

In conclusion, there are multiple ways of generating UUIDs in Bash. Moreover, one can choose the algorithm on effect while generating hash-based UUIDs using uuidgen command. The Python uuid module also offers the flexibility to generate UUIDs with different types of randomness. I believe from now on you can generate a UUID in Bash with the quickest amount of time.

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