apt-*: add more info links; apt-file: add regex search example

pages/linux/apt-add-repository.md

@@ -1,6 +1,7 @@
 # apt-add-repository
 
 > Manages apt repository definitions.
+> More information: <https://manned.org/apt-add-repository.1>.
 
 - Add a new apt repository:
 

pages/linux/apt-cache.md

@@ -1,6 +1,7 @@
 # apt-cache
 
 > Debian and Ubuntu package query tool.
+> More information: <https://manned.org/apt-cache.8>.
 
 - Search for a package in your current sources:
 

pages/linux/apt-file.md

@@ -1,15 +1,20 @@
 # apt-file
 
 > Search for files in apt packages, including ones not yet installed.
+> More information: <https://manned.org/apt-file.1>.
 
 - Update the metadata database:
 
 `sudo apt update`
 
 - Search for packages that contain the specified file or path:
 
-`apt-file search {{part/of/filename}}`
+`apt-file {search|find} {{part/of/filename}}`
 
 - List the contents of a specific package:
 
-`apt-file list {{package_name}}`
+`apt-file {show|list} {{package_name}}`
+
+- Search for packages that match the regular expresssion given in `pattern`:
+
+`apt-file {search|find} --regexp {{pattern}}

pages/linux/apt-get.md

@@ -2,6 +2,7 @@
 
 > Debian and Ubuntu package management utility.
 > Search for packages using `apt-cache`.
+> More information: <https://manned.org/apt-get.8>.
 
 - Update the list of available packages and versions (it's recommended to run this before other `apt-get` commands):
 

pages/linux/apt-key.md

@@ -1,6 +1,9 @@
 # apt-key
 
 > Key management utility for the APT Package Manager on Debian and Ubuntu.
+> Be carefull as `apt-key` is now deprecated except for the use of `apt-key del`
+> in maintainer scripts to remove existing keys from the main keyring.
+> More information: <https://manned.org/apt-key.8>.
 
 - List trusted keys:
 

pages/linux/apt.md

@@ -2,6 +2,7 @@
 
 > Package management utility for Debian based distributions.
 > Recommended replacement for apt-get when used interactively in Ubuntu versions 16.04 and later.
+> More information: <https://manned.org/apt.8>.
 
 - Update the list of available packages and versions (it's recommended to run this before other `apt` commands):
 

pages/linux/aptitude.md

@@ -1,6 +1,7 @@
 # aptitude
 
 > Debian and Ubuntu package management utility.
+> More information: <https://manned.org/aptitude.8>.
 
 - Synchronize list of packages and versions available. This should be run first, before running subsequent aptitude commands: