feat(check-user): add new exercise for scripting piscine

sh/tests/check-user_test.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# set -euo pipefail
+IFS='
+'
+
+script_dirS=$(cd -P "$(dirname "$BASH_SOURCE")" &>/dev/null && pwd)
+
+challenge() {
+    submitted="./check-user.sh $@
+    "
+    expected="./check-user.sh $@
+    "
+    submitted+=$(2>&1 bash "$script_dirS"/student/check-user.sh "$@")
+    expected+=$(2>&1 bash "$script_dirS"/solutions/check-user.sh "$@")
+
+    diff -U 1 <(echo "$submitted") <(echo "$expected")
+}
+
+challenge "-i" "root"
+challenge "-e" "root"
+
+challenge "-i" "unknown_not_found"
+challenge "-e" "unknown_not_found"
+
+challenge
+challenge "-i" "root" "too" "many" "args"
+challenge "-t" "root"
+

sh/tests/solutions/check-user.sh

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+#!/usr/bin/env bash
+
+set -euo pipefail
+IFS='
+'
+
+if [ $# != 2 ]
+then
+    >&2 echo "Error: expect 2 arguments"
+    exit 1
+elif [[ $1 == "-e" ]]
+then
+    user_info=$(getent passwd $2)
+    if [[ $user_info == "" ]]
+    then
+        echo no
+    else
+        echo yes
+    fi
+elif [[ $1 == "-i" ]]
+then
+    getent passwd $2
+else
+    >&2 echo "Error: unknown flag"
+    exit 1
+fi

subjects/devops/check-user/README.md

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+## Check User
+
+### Instructions
+
+In this exercise you will make a script `check-user.sh` that will take 2 arguments and return information about the selected user, always ended by a new line.
+
+The first argument will be a flag defining the behavior of the script:
+- `-e`: check if the user exists, returns `yes` or `no` appropriately.
+- `-i`: returns information about the user.
+
+The second argument will be the name of the checked user.
+
+> The information about the user will be formatted in the same way it appears in `/etc/passwd`.
+
+### Usage
+
+```console
+$ ./check-user.sh -e root
+yes
+$ ./check-user.sh -i root
+root:x:0:0:root:/root:/bin/bash
+$ ./check-user.sh -e unknown
+no
+$ ./check-user.sh -i unknown
+$
+```
+
+> Your results may appear slightly different.
+
+### Error handling
+
+All errors will print a specific message on **stderr** (ending with a newline) and returns a specific non-zero value:
+- Wrong number of arguments: `"Error: expect 2 arguments"`, returns `1`.
+- First argument different from `-e` or `-i`: `"Error: unknown flag"`, exit with `1`.
+
+### Hints
+
+> `man getent` will be a great resource to explore  
+> [List Linux users](https://linuxize.com/post/how-to-list-users-in-linux/)