Add a couple of questions

exercises/shell/solutions/basic_date.md

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+## Basic Date
+
+### Objectives
+
+1. Write a script that will put the current date in a file called "the_date.txt"
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+echo $(date) > the_date.txt
+```

exercises/shell/solutions/count_chars.md

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+## Count Chars
+
+### Objectives
+
+1. Read input from the user until you get empty string
+2. For each of the lines you read, count the number of characters and print it
+
+### Constraints
+
+1. You must use a while loop
+2. Assume at least three lines of input
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+echo -n "Please insert your input: "
+
+while read line; do
+    echo -n "$line" | wc -c
+    echo -n "Please insert your input: "
+done
+```

exercises/shell/solutions/empty_files.md

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+## Empty Files
+
+### Objectives
+
+1. Write a script to remove all the empty files in a given directory (including nested directories)
+
+### Solution
+
+```
+#! /bin/bash
+for x in *
+do
+    if [ -s $x ]
+    then
+        continue
+    else
+        rm -rf $x
+    fi
+done
+```

exercises/shell/solutions/factors.md

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+## Shell Scripting - Factors
+
+### Objectives
+
+Write a script that when given a number, will:
+
+* Check if the number has 2 as factor, if yes it will print "one factor"
+* Check if the number has 3 as factor, if yes it will print "one factor...actually two!"
+* If none of them (2 and 3) is a factor, print the number itself
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+(( $1 % 2 )) || res="one factor"
+(( $1 % 3 )) || res+="...actually two!"
+
+echo ${res:-$1}
+```

exercises/shell/solutions/files_size.md

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+## Files Size
+
+### Objectives
+
+1. Print the name and size of every file and directory in current path
+
+Note: use at least one for loop!
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+for i in $(ls -S1); do
+    echo $i: $(du -sh "$i" | cut -f1)
+done 
+```

exercises/shell/solutions/great_day.md

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+## Great Day
+
+### Objectives
+
+1. Write a script that will print "Today is a great day!" unless it's given a day name and then it should print "Today is <given day>"
+
+Note: no need to check whether the given argument is actually a valid day
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+echo "Today is ${1:-a great day!}"
+```

exercises/shell/solutions/hello_world.md

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+## Shell Scripting - Hello World
+
+### Objectives
+
+1. Define a variable with the string 'Hello World'
+2. Print the value of the variable you've defined and redirect the output to the file "amazing_output.txt"
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+HW_STR="Hello World"
+echo $HW_STR > amazing_output.txt
+```

exercises/shell/solutions/host_status.md

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+## It's Alive!
+
+### Objectives
+
+1. Write a script to determine whether a given host is down or up
+
+### Solution
+
+```
+#!/usr/bin/env bash
+SERVERIP=<IP Address>
+NOTIFYEMAIL=test@example.com
+
+ping -c 3 $SERVERIP > /dev/null 2>&1
+if [ $? -ne 0 ]
+then
+   # Use mailer here:
+   mailx -s "Server $SERVERIP is down" -t "$NOTIFYEMAIL" < /dev/null
+fi
+```

exercises/shell/solutions/num_of_args.md

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+## Number of Arguments
+
+### Objectives
+
+* Write a script that will print "Got it: <argument value>" in case of one argument
+* In case no arguments were provided, it will print "Usage: ./<program name> <argument>"
+* In case of more than one argument, print "hey hey...too many!"
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+set -eu
+
+main() {
+  case $# in
+    0) printf "%s" "Usage: ./<program name> <argument>"; return 1 ;;
+    1) printf "%s" "Got it: $1"; return 0 ;;
+    *) return 1 ;;
+  esac
+}
+
+main "$@"
+```
+

exercises/shell/solutions/sum.md

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+## Sum
+
+### Objectives
+
+1. Write a script that gets two numbers and prints their sum
+3. Make sure the input is valid (= you got two numbers from the user)
+2. Test the script by running and passing it two numbers as arguments 
+
+### Constraints
+
+1. Use functions
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+re='^[0-9]+$'
+
+if ! [[ $1 =~ $re && $2 =~ $re ]]; then
+    echo "Oh no...I need two numbers"
+    exit 2
+fi
+
+function sum {
+    echo $(( $1 + $2 ))
+}
+
+sum $1 $2
+```