Merge pull request #724 from bdu-birhanu/feat_shell_tool

add information on shell tools

docs/workflow_solutions/shell.md

@@ -12,6 +12,11 @@ We are not responsible for accidental deletions or overwrites caused inadvertent
 
 The internet has thousands of guides for using the shell. Rather than devise our own complete lesson plan for using the shell, we recommend finding and using one of the high-quality lessons available on the internet. The Software Carpentries group offers a number of high-quality online lesson plans for introductory computing and data science tools. While these lesson plans are intended to be delivered by an instructor in a classroom setting, they can be still be useful to follow solo. For the shell lesson, see <https://swcarpentry.github.io/shell-novice/>.
 
+There are also additional resources that aid in learning and verifying shell commands and scripts:
+
+- [Explain Shell](https://explainshell.com/): An educational tool providing detailed explanations of individual commands in relatively reasonably-plain English. This tool doesn't explain what a command does at a high level nor its purpose or intent, only the details of the parts making up the command.
+- [ShellCheck](https://www.shellcheck.net/): An online tool for conducting static analysis checks on shell scripts. The Git repository for this tool can be found [here](https://github.com/koalaman/shellcheck ) and it can also be installed via [Anaconda]( https://anaconda.org/conda-forge/shellcheck).
+
 At the shell prompt, you can also use the command `curl cheat.sh/<command>` to get a simple-to-understand explanation of what the command does and how to use it (see [curl](#download-files-from-internet-sources-curl)). Below is an example for the [pwd command](#show-working-directory-pwd).
 
 ![!curl of site cheat.sh/pwd](images/curl_cheat_sh_pwd.png)