Add `show` command and use that for `list` searches

Displaying a record pair for a hostname or IP address is likely a common
operation, and using the `show` name makes it clear what the primary
function of the command is. Since record pairs are very simple, the
easiest way to allow both hostname and ip address arguments is to use
grep, which also provides general search-like functionality. In order to
avoid doubling this functionality, use the `show` command in the `list`
command for search.

Readme.md

@@ -8,6 +8,7 @@ A command line program with shortcuts for managing hosts file entries.
       hosts add <ip> <hostname>
       hosts remove <hostname>
       hosts list [<search string>]
+      hosts show ( <ip> | <hostname> | <search string> )
       hosts edit
       hosts file
 

hosts

@@ -694,15 +694,15 @@ file() {
 
 desc list <<EOM
 Usage:
-  $_me list [127.]
+  $_me list [<search string>]
 
 Description:
-  List the existing IP / hostname pairs. When provided with the beginning of
-  an IP address, lists the pairs with matching IP addresses.
+  List the existing IP / hostname pairs. When provided with a seach string, all
+  matching lines will be printed.
 EOM
 list() {
   if [[ -n "$1" ]]; then
-    grep "^[^#]*$1" /etc/hosts
+    $_me show "$1"
   else
     # NOTE: use separate expressions since using a | for the or results in
     # inconsistent behavior.
@@ -729,6 +729,24 @@ remove() {
   fi
 }
 
+# ------------------------------------------------------------------------ show
+
+desc show <<EOM
+Usage:
+  $_me show ( <ip> | <hostname> | <search string> )
+
+Description:
+  Print entries matching a given IP address, hostname, or search string.
+EOM
+show() {
+  if [[ -n "$1" ]]; then
+    grep "^[^#]*$1" /etc/hosts
+  else
+    $_me help show
+    exit 1
+  fi
+}
+
 ###############################################################################
 # Run Program
 ###############################################################################