Help

Running the tests

Each exercise contains a test file. Run the tests using the bats program.

bats hello_world.bats

bats will need to be installed. See the Testing on the Bash track page for instructions to install bats for your system.

Help for assert functions

The tests use functions from the bats-assert library. Help for the various assert* functions can be found there.

Debugging output

This works locally with `bats`, but **not** in the Exercism online editor.

When running tests, bats captures both stdout and stderr for comparison with the expected output. If you print debug messages to stdout (echo) or stderr (>&2), they will be included in the captured output and may cause the test to fail.

To print debug information without affecting the test results, bats provides file descriptor 3 for this purpose. Anything redirected to >&3 will be shown during the test run but will not be included in the captured output used for assertions.

Example:

#!/usr/bin/env bash

# This debug message will not interfere with test output comparison
echo "debug message" >&3

# Normal program output (this is what your tests will see and compare)
echo "Hello, World!"

Example run:

$ bats hello_world.bats
hello_world.bats
 ✓ Say Hi!
debug message
1 test, 0 failures

This allows you to see helpful debug output without affecting the tests.

Skipped tests

Solving an exercise means making all its tests pass. By default, only one test (the first one) is executed when you run the tests. This is intentional, as it allows you to focus on just making that one test pass. Once it passes, you can enable the next test by commenting out or removing the next annotation:

[[ $BATS_RUN_SKIPPED == true ]] || skip

Overriding skips

To run all tests, including the ones with skip annotations, you can run:

BATS_RUN_SKIPPED=true bats exercise_name.bats

It can be convenient to use a wrapper function to save on typing:

bats() {
    BATS_RUN_SKIPPED=true command bats *.bats
}

Then run tests with just:

bats

Submitting your solution

You can submit your solution using the exercism submit hello_world.sh command. This command will upload your solution to the Exercism website and print the solution page's URL.

It's possible to submit an incomplete solution which allows you to:

See how others have completed the exercise
Request help from a mentor

Need to get help?

If you'd like help solving the exercise, check the following pages:

Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.

Check your code for syntax errors: paste your code into https://shellcheck.net (or install it on your machine).

Stack Overflow will be your first stop for bash questions.

start with the bash tag to search for your specific question: it's probably already been asked
under the bash tag on Stackoverflow, the Learn more... link has tons of good information.
- the "Books and Resources" section is particularly useful.
the bash tag on Unix & Linux is also active

External utilities

bash is a language to write "scripts" -- programs that can call external tools, such as sed, awk, date and even programs written in other programming languages, like Python. This track does not restrict the usage of these utilities, and as long as your solution is portable between systems and does not require installation of third party applications, feel free to use them to solve the exercise.

For an extra challenge, if you would like to have a better understanding of the language, try to re-implement the solution in pure bash, without using any external tools. There are some types of problems that bash cannot solve, such as floating point arithmetic and manipulating dates: for those, you must call out to an external tool.

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