feat(env-format): add subject, test and solution for the exercise

sh/tests/env-format_test.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+# Unofficial Bash Strict Mode
+set -euo pipefail
+IFS='
+'
+
+FILENAME="student/env-format.sh"
+
+# True if FILE exists and is a regular file
+if [ -f ${FILENAME} ]; then
+    # FILE exists and it's not empty
+    if [ -s ${FILENAME} ]; then
+        if [[ $(cat $FILENAME | grep echo | wc -l) -ne 0 ]]; then
+            echo "echo is not allowed in this exercise!"
+            exit 1
+        fi
+        submitted=$(bash $FILENAME)
+        expected=$(bash solutions/env-format.sh)
+        diff <(echo "$submitted") <(echo "$expected")
+    else
+        echo "The file exist but is empty"
+        exit 1
+    fi
+else
+    echo "File does not exist"
+    exit 1
+fi

sh/tests/solutions/env-format.sh

@@ -0,0 +1,2 @@
+printenv PWD
+printenv | grep "H" | awk -F "=" '{print $1}'

subjects/devops/env-format/README.md

@@ -0,0 +1,113 @@
+## Env-format
+
+### Instructions
+
+Create a script `env-format.sh`, which will print the environment variables that have the following formats:
+
+- Print the `PWD` value.
+- All the environment variables that have a letter `H` in the name, without printing the value of those variables.
+
+```console
+$ print env
+SHELL=/bin/bash
+QT_ACCESSIBILITY=1
+NVM_RC_VERSION=
+COLORTERM=truecolor
+HOMEBREW_PREFIX=/home/linuxbrew/.linuxbrew
+DESKTOP_SESSION=i3
+...
+PWD=/home/user
+LOGNAME=user
+MANPATH=/home/linuxbrew/.linuxbrew/share/man:
+XDG_SESSION_DESKTOP=i3
+XAUTHORITY=/run/user/1000/gdm/Xauthority
+WINDOWPATH=2
+SHELL=/bin/bash
+SSH_AGENT_PID=2900
+HOME=/home/user
+HOMEBREW_SHELLENV_PREFIX=/home/linuxbrew/.linuxbrew
+USERNAME=user
+$
+```
+
+Expected output:
+
+```console
+$ ./env-format.sh
+/home/user/Documents/public/sh/tests/student
+SHELL
+SSH_AGENT_PID
+HOMEBREW_SHELLENV_PREFIX
+MANPATH
+XAUTHORITY
+WINDOWPATH
+HOME
+$
+```
+
+### Hints
+
+Environment variables are variables that contain values necessary to set up a shell environment. Contrary to shell variables, environment variables persist in the shell’s child processes.
+
+```console
+VARIABLE_NAME=value
+```
+
+Most Common Environment Variables:
+
+- PWD – Current working directory.
+- HOME – The user’s home directory location.
+- SHELL – Current shell (bash, zsh, etc.).
+- LOGNAME – Name of the user.
+- UID – User’s unique identifier.
+- HOSTNAME – Device’s hostname on the network.
+- MAIL – User’s mail directory.
+- EDITOR – The Linux system default text editor.
+- TEMP – Directory location for temporary files.
+
+How to Check Environment Variables:
+
+Structurally, environment and shell variables are the same – both are a key-value pair, separated by an equal sign.
+
+- `printenv`. Prints the values of all or some environment variables.
+
+```console
+$ printenv HOME
+/home/user
+```
+
+Search Specific Environment Variables:
+
+To find all the variables containing a certain character or pattern, use the `grep` command:
+
+```console
+$ printenv | grep "W"
+HOMEBREW_PREFIX=/home/linuxbrew/.linuxbrew
+HOMEBREW_SHELLENV_PREFIX=/home/linuxbrew/.linuxbrew
+PWD=/home/user/Documents/
+WINDOWPATH=2
+OLDPWD=/home/user/Public
+```
+
+- awk. The awk command is a Linux tool and programming language that allows users to process and manipulate data and produce formatted reports.
+
+This flag will come in handy:
+
+`-F` [separator] Used to specify a file separator. The default separator is a blank space.
+
+```console
+$ cat example.txt
+Hello:my:name:is:John
+$ awk -F ":" '{print $5}' example.txt
+John
+$
+```
+
+> You have to use Man or Google to know more about commands flags, in order to solve this exercise!
+> Google and Man will be your friends!
+
+### References
+
+- [printenv](https://www.gnu.org/software/coreutils/manual/html_node/printenv-invocation.html#printenv-invocation).
+- [grep](https://www.gnu.org/software/grep/manual/grep.html).
+- [awk](https://www.ibm.com/docs/en/zos/2.4.0?topic=descriptions-awk-process-programs-written-in-awk-language)