attr: add page (#22700)

pages/common/attr.md

@@ -0,0 +1,24 @@
+# attr
+
+> Manipulate extended attributes on filesystem objects.
+> More information: <https://manned.org/attr>.
+
+- List the names and sizes of all extended attributes of a file:
+
+`attr -l {{path/to/file}}`
+
+- Get the value of an extended attribute:
+
+`attr -g {{attribute_name}} {{path/to/file}}`
+
+- Set an extended attribute value:
+
+`attr -s {{attribute_name}} -V "{{attribute_value}}" {{path/to/file}}`
+
+- Set an extended attribute using a value from `stdin`:
+
+`echo "{{attribute_value}}" | attr -s {{attribute_name}} {{path/to/file}}`
+
+- Remove an extended attribute:
+
+`attr -r {{attribute_name}} {{path/to/file}}`