diff --git a/knowledge base/date.md b/knowledge base/date.md
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+++ b/knowledge base/date.md	
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+# Date
+
+1. [TL;DR](#tldr)
+
+## TL;DR
+
+```sh
+# Print the current date in the 'YYYY-MM-DD' format.
+date '+%F'
+date '+%Y-%m-%d'
+
+# Print the current date in the 'YYYY-MM-DDThh:mm:SS' format.
+date '+%FT%T'
+date '+%Y-%m-%dT%H:%M:%S'
+```
diff --git a/knowledge base/touch.md b/knowledge base/touch.md
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+# Touch
+
+1. [TL;DR](#tldr)
+
+## TL;DR
+
+```sh
+# Change the access and modification date of files.
+# End the time with 'Z' to specify the new time is UTC instead of local time.
+touch -cd '2017-08-15T13:28:42' '20170815_132842.mp4'
+touch -cd '2017-08-15T12:28:42Z' '20170815_132842.mp4'
+```