Updated linux bash completion (#44961)

scripts/vcpkg_completion.bash

@@ -1,17 +1,32 @@
-#/usr/bin/env bash
+#!/usr/bin/env bash
+# set -x
+
+# To install:
+#  > vcpkg integrate bash
+#    This adds the following line to ~/.bashrc:
+#      source ~/vcpkg/scripts/vcpkg_completion.bash
+
+# Details: bash and utilities from bash-completion
+#          Bash commands: compgen, complete
+# Input: COMP_WORDS, COMP_CWORD, COMP_LINE, COMP_POINT, COMP_KEY, COMP_WORDBREAKS
+# Output: COMPREPLY
 
 _vcpkg_completions()
 {
-  local vcpkg_executable=${COMP_WORDS[0]}
-  local remaining_command_line=${COMP_LINE:(${#vcpkg_executable}+1)}
-  COMPREPLY=($(${vcpkg_executable} autocomplete "${remaining_command_line}" -- 2>/dev/null))
+    local vcpkg_executable=${COMP_WORDS[0]}
+    local remaining_command_line=${COMP_LINE:(${#vcpkg_executable}+1)}
+    # echo "rem:$remaining_command_line"
 
-  # Colon is treated as a delimiter in bash. The following workaround
-  # allows triplet completion to work correctly in the syntax:
-  # zlib:x64-windows
-  local cur
-  _get_comp_words_by_ref -n : cur
-  __ltrim_colon_completions "$cur"
+    if [ $COMP_CWORD -eq 1 ]; then
+        local opts=$(${vcpkg_executable} autocomplete ${remaining_command_line})
+    else
+        local opts=$(${vcpkg_executable} autocomplete ${remaining_command_line} --)
+    fi
+    #echo "opts:$opts"
+
+    COMPREPLY=($(compgen -W "${opts}" -- ${COMP_WORDS[COMP_CWORD]}) )
+    #echo "COMPREPLY:$COMPREPLY"
 }
 
 complete -F _vcpkg_completions vcpkg
+