Merge pull request #929 from slash3b/at

at: add page

pages/linux/at.md

@@ -0,0 +1,15 @@
+# at
+
+> Executes commands at a specified time.
+
+- Open an `at` prompt to create a new set of scheduled commands, press Ctrl+D to save and exit:
+
+`at {{hh:mm:ss}}`
+
+- Execute the commands and email the result using a local mailing program such as sendmail:
+
+`at {{hh:mm:ss}} -m`
+
+- Execute a script at the given time:
+
+`at {{hh:mm:ss}} -f {{path/to/file}}`