Do not specify absolute paths to utilities

Specifying an absolute path to utilities is no longer needed,
since environment filtering uses a default PATH.

Library/Homebrew/brew.sh

@@ -85,7 +85,7 @@ case "$HOMEBREW_SYSTEM" in
   Linux)  HOMEBREW_LINUX="1" ;;
 esac
 
-HOMEBREW_CURL="/usr/bin/curl"
+HOMEBREW_CURL="curl"
 if [[ -n "$HOMEBREW_MACOS" ]]
 then
   HOMEBREW_PROCESSOR="$(uname -p)"
@@ -136,7 +136,7 @@ else
   fi
 fi
 HOMEBREW_USER_AGENT="$HOMEBREW_PRODUCT/$HOMEBREW_USER_AGENT_VERSION ($HOMEBREW_SYSTEM; $HOMEBREW_PROCESSOR $HOMEBREW_OS_USER_AGENT_VERSION)"
-HOMEBREW_CURL_VERSION="$("$HOMEBREW_CURL" --version 2>/dev/null | head -n1 | /usr/bin/awk '{print $1"/"$2}')"
+HOMEBREW_CURL_VERSION="$("$HOMEBREW_CURL" --version 2>/dev/null | head -n1 | awk '{print $1"/"$2}')"
 HOMEBREW_USER_AGENT_CURL="$HOMEBREW_USER_AGENT $HOMEBREW_CURL_VERSION"
 
 # Declared in bin/brew

Library/Homebrew/keg_relocate.rb

@@ -96,7 +96,7 @@ class Keg
   alias generic_recursive_fgrep_args recursive_fgrep_args
 
   def each_unique_file_matching(string)
-    Utils.popen_read("/usr/bin/fgrep", recursive_fgrep_args, string, to_s) do |io|
+    Utils.popen_read("fgrep", recursive_fgrep_args, string, to_s) do |io|
       hardlinks = Set.new
 
       until io.eof?
@@ -113,7 +113,7 @@ class Keg
 
   def text_files
     text_files = []
-    return text_files unless File.exist?("/usr/bin/file")
+    return text_files unless which("file") && which("xargs")
 
     # file has known issues with reading files on other locales. Has
     # been fixed upstream for some time, but a sufficiently new enough
@@ -132,7 +132,7 @@ class Keg
         end
         false
       }
-      output, _status = Open3.capture2("/usr/bin/xargs -0 /usr/bin/file --no-dereference --print0",
+      output, _status = Open3.capture2("xargs -0 file --no-dereference --print0",
                                        stdin_data: files.to_a.join("\0"))
       # `file` output sometimes contains data from the file, which may include
       # invalid UTF-8 entities, so tell Ruby this is just a bytestring

Library/Homebrew/utils.rb

@@ -344,7 +344,7 @@ def which_editor
   editor = %w[atom subl mate edit vim].find do |candidate|
     candidate if which(candidate, ENV["HOMEBREW_PATH"])
   end
-  editor ||= "/usr/bin/vim"
+  editor ||= "vim"
 
   opoo <<~EOS
     Using #{editor} because no editor was set in the environment.

Library/Homebrew/utils/curl.rb

@@ -3,7 +3,7 @@ require "open3"
 
 def curl_executable
   curl = Pathname.new ENV["HOMEBREW_CURL"]
-  curl = Pathname.new "/usr/bin/curl" unless curl.exist?
+  curl = which("curl") unless curl.exist?
   return curl if curl.executable?
   raise "#{curl} is not executable"
 end