добавил хэлперы для проверки наличия файла и проверки даты модификации даты

src/io.sh

@@ -2,8 +2,22 @@
 
 filePutContent() {
   local FILE_PATH=$1
-  DIRECTORY_PATH=$(dirname $FILE_PATH)
+  DIRECTORY_PATH=$(dirname "$FILE_PATH")
-  mkdir -p $DIRECTORY_PATH
+  mkdir -p "$DIRECTORY_PATH"
-  touch $FILE_PATH
+  touch "$FILE_PATH"
-  echo $2 >> $FILE_PATH
+  echo "$2" >> "$FILE_PATH"
 }
+
+fileExists() {
+  if [ -f "$1" ];
+  then
+    echo "1"
+  fi
+}
+
+fileModifiedOlder() {
+  if [ "$(find "$1" -type f -mtime "$2")" ];
+  then
+    echo "1"
+  fi
+}

src/io.test.sh

@@ -2,8 +2,21 @@
 
 . ./io.sh
 
-filePutContent ./temp.txt "Content was added successfuly1"
+filePutContent ./temp.txt "Content was added successfully1"
-filePutContent ./temp.txt "Content was added successfuly2"
+
+[ "$(fileExists ./temp.txt)" ] && echo "File exists"
+
+filePutContent ./temp.txt "Content was added successfully2"
 
 cat ./temp.txt
-unlink ./temp.txt
+unlink ./temp.txt
+
+[ ! "$(fileExists ./temp.txt)" ] && echo "File not exists"
+
+today="$(date +%Y-%m-%d)"
+nextDate=$(date +%Y-%m-%d -d "$today - 3 days")
+
+touch -mad "$nextDate 00:00:01" ./temp
+[ "$(fileModifiedOlder ./temp 3)" ] && echo "File is older 3 days"
+[ ! "$(fileModifiedOlder ./temp 4)" ] && echo "File is not older 4 days"
+unlink ./temp