diff --git a/libexec/pyenv-commands b/libexec/pyenv-commands
index 70f9bcfa..547fd265 100755
--- a/libexec/pyenv-commands
+++ b/libexec/pyenv-commands
@@ -8,40 +8,35 @@ set -e
 # Provide pyenv completions
 if [ "$1" = "--complete" ]; then
   echo --sh
-  echo --fish
   echo --no-sh
   exit
 fi
 
-if [ "$1" = "--sh" ] || [ "$1" = "--fish" ]; then
-  sh="${1##--}-"
+if [ "$1" = "--sh" ]; then
+  sh=1
   shift
-elif [ "$1" = "--no-sh" ] || [ "$1" = "--no-fish" ]; then
+elif [ "$1" = "--no-sh" ]; then
   nosh=1
   shift
 fi
 
+IFS=: paths=($PATH)
+
 shopt -s nullglob
 
-{ for path in ${PATH//:/$'\n'}; do
+{ for path in "${paths[@]}"; do
     for command in "${path}/pyenv-"*; do
       command="${command##*pyenv-}"
       if [ -n "$sh" ]; then
-        if [[ "${command}" == "${sh}"* ]]; then
-          echo "${command##${sh}}"
+        if [ ${command:0:3} = "sh-" ]; then
+          echo ${command##sh-}
         fi
       elif [ -n "$nosh" ]; then
-        if [ "${command:0:3}" != "sh-" ] && [ "${command:0:5}" != "fish-" ]; then
-          echo "$command"
+        if [ ${command:0:3} != "sh-" ]; then
+          echo ${command##sh-}
         fi
       else
-        if [ "${command:0:3}" = "sh-" ]; then
-          echo "${command##sh-}"
-        elif [ "${command:0:5}" = "fish-" ]; then
-          echo "${command##fish-}"
-        else
-          echo "${command}"
-        fi
+        echo ${command##sh-}
       fi
     done
   done
diff --git a/libexec/pyenv-completions b/libexec/pyenv-completions
index 385abcc7..9fe54879 100755
--- a/libexec/pyenv-completions
+++ b/libexec/pyenv-completions
@@ -10,8 +10,8 @@ if [ -z "$COMMAND" ]; then
   exit 1
 fi
 
-COMMAND_PATH="$(command -v "pyenv-$COMMAND" || command -v "pyenv-sh-$COMMAND" || command -v "pyenv-fish-$COMMAND")"
-if grep -i "^# provide pyenv completions" "$COMMAND_PATH" >/dev/null; then
+COMMAND_PATH="$(command -v "pyenv-$COMMAND" || command -v "pyenv-sh-$COMMAND")"
+if grep -i "^\([#%]\|--\|//\) provide pyenv completions" "$COMMAND_PATH" >/dev/null; then
   shift
   exec "$COMMAND_PATH" --complete "$@"
 fi
diff --git a/libexec/pyenv-fish-shell b/libexec/pyenv-fish-shell
deleted file mode 100755
index 6c4376d4..00000000
--- a/libexec/pyenv-fish-shell
+++ /dev/null
@@ -1,52 +0,0 @@
-#!/usr/bin/env bash
-#
-# Summary: Set or show the shell-specific Python version
-#
-# Usage: pyenv shell <version>
-#        pyenv shell --unset
-#
-# Sets a shell-specific Python version by setting the `PYENV_VERSION'
-# environment variable in your shell. This version overrides local
-# application-specific versions and the global version.
-#
-# <version> should be a string matching a Python version known to pyenv.
-# The special version string `system' will use your default system Python.
-# Run `pyenv versions' for a list of available Python versions.
-
-set -e
-[ -n "$PYENV_DEBUG" ] && set -x
-
-# Provide pyenv completions
-if [ "$1" = "--complete" ]; then
-  echo --unset
-  echo system
-  exec pyenv-versions --bare
-fi
-
-versions=("$@")
-
-if [ -z "$versions" ]; then
-  if [ -z "$PYENV_VERSION" ]; then
-    echo "pyenv: no shell-specific version configured" >&2
-    exit 1
-  else
-    echo "echo \"\$PYENV_VERSION\""
-    exit
-  fi
-fi
-
-if [ "$versions" = "--unset" ]; then
-  echo "set -e PYENV_VERSION"
-  exit
-fi
-
-# Make sure the specified version is installed.
-if pyenv-prefix "${versions[@]}" >/dev/null; then
-  OLDIFS="$IFS"
-  IFS=: PYENV_VERSION="${versions[*]}"
-  IFS="OLDIFS"
-  echo "setenv PYENV_VERSION \"${PYENV_VERSION}\""
-else
-  echo "false"
-  exit 1
-fi
diff --git a/libexec/pyenv-help b/libexec/pyenv-help
index abce46ca..9b7f7e4a 100755
--- a/libexec/pyenv-help
+++ b/libexec/pyenv-help
@@ -17,7 +17,7 @@ set -e
 
 command_path() {
   local command="$1"
-  command -v pyenv-"$command" || command -v pyenv-sh-"$command" || command -v pyenv-fish-"$command" || true
+  command -v pyenv-"$command" || command -v pyenv-sh-"$command" || true
 }
 
 extract_initial_comment_block() {
@@ -64,8 +64,8 @@ collect_documentation() {
     }
 
     function trim(str) {
-      gsub(/^\n*/, "", str)
-      gsub(/\n*$/, "", str)
+      sub(/^\n*/, "", str)
+      sub(/\n*$/, "", str)
       return str
     }
 
diff --git a/libexec/pyenv-init b/libexec/pyenv-init
index 44eb4cfa..25a029b0 100755
--- a/libexec/pyenv-init
+++ b/libexec/pyenv-init
@@ -11,7 +11,7 @@ for args in "$@"
 do
   if [ "$args" = "-" ]; then
     print=1
-		shift
+    shift
   fi
 
   if [ "$args" = "--no-rehash" ]; then
@@ -25,8 +25,14 @@ if [ -z "$shell" ]; then
   shell="$(basename "$SHELL")"
 fi
 
+READLINK=$(type -p greadlink readlink | head -1)
+if [ -z "$READLINK" ]; then
+  echo "pyenv: cannot find readlink - are you missing GNU coreutils?" >&2
+  exit 1
+fi
+
 resolve_link() {
-  $(type -p greadlink readlink | head -1) $1
+  $READLINK "$1"
 }
 
 abs_dirname() {
@@ -67,7 +73,14 @@ if [ -z "$print" ]; then
   { echo "# Load pyenv automatically by adding"
     echo "# the following to ${profile}:"
     echo
-    echo 'eval "$(pyenv init -)"'
+    case "$shell" in
+    fish )
+      echo '. (pyenv init -|psub)'
+      ;;
+    * )
+      echo 'eval "$(pyenv init -)"'
+      ;;
+    esac
     echo
   } >&2
 
@@ -76,54 +89,58 @@ fi
 
 mkdir -p "${PYENV_ROOT}/"{shims,versions}
 
-case "$shell" in
-fish )
-  echo 'setenv PATH "'${PYENV_ROOT}'/shims"' '$PATH' ';'
+if [[ ":${PATH}:" != *:"${PYENV_ROOT}/shims":* ]]; then
+  case "$shell" in
+  fish )
+    echo "setenv PATH '${PYENV_ROOT}/shims' \$PATH"
   ;;
-* )
-  echo 'export PATH="'${PYENV_ROOT}'/shims:${PATH}"'
+  * )
+    echo 'export PATH="'${PYENV_ROOT}'/shims:${PATH}"'
   ;;
-esac
+  esac
+fi
 
-case "$shell" in
-bash | zsh )
-  echo "source \"$root/completions/pyenv.${shell}\""
-  ;;
-fish )
-  echo ". \"$root/completions/pyenv.${shell}\";"
-  ;;
-esac
+completion="${root}/completions/pyenv.${shell}"
+[ -r "$completion" ] && echo ". '$completion'"
 
 if [ -z "$no_rehash" ]; then
   echo 'pyenv rehash 2>/dev/null'
 fi
 
+commands=(`pyenv-commands --sh`)
 case "$shell" in
 fish )
-  commands=(`pyenv-commands --fish`)
   cat <<EOS
-;function pyenv;
-  set -e command;
-  set command \$argv[1];
-  if [ (count \$argv) -gt 0 ];
-    set -e argv[1];
-  end;
-
-  switch "\$command";
-    case ${commands[*]};
-      eval (pyenv "fish-\$command" \$argv);
-    case '*';
-      command pyenv "\$command" \$argv;
-  end;
-end;
+function pyenv
+  set command \$argv[1]
+  set -e argv[1]
+
+  switch "\$command"
+  case ${commands[*]}
+    eval (pyenv "sh-\$command" \$argv)
+  case '*'
+    command pyenv "\$command" \$argv
+  end
+end
+EOS
+  exit 0
+  ;;
+ksh )
+  cat <<EOS
+function pyenv {
+  typeset command
 EOS
   ;;
 * )
-  commands=(`pyenv-commands --sh`)
-  IFS="|"
   cat <<EOS
 pyenv() {
-  typeset command
+  local command
+EOS
+  ;;
+esac
+
+IFS="|"
+cat <<EOS
   command="\$1"
   if [ "\$#" -gt 0 ]; then
     shift
@@ -131,11 +148,9 @@ pyenv() {
 
   case "\$command" in
   ${commands[*]})
-    eval \`pyenv "sh-\$command" "\$@"\`;;
+    eval "\`pyenv "sh-\$command" "\$@"\`";;
   *)
     command pyenv "\$command" "\$@";;
   esac
 }
 EOS
-  ;;
-esac
diff --git a/libexec/pyenv-sh-rehash b/libexec/pyenv-sh-rehash
index 5d94d651..e117d8b9 100755
--- a/libexec/pyenv-sh-rehash
+++ b/libexec/pyenv-sh-rehash
@@ -7,7 +7,19 @@ if [ "$1" = "--complete" ]; then
   exec pyenv-rehash --complete
 fi
 
+shell="$(basename "$SHELL")"
+
 # When pyenv shell integration is enabled, delegate to pyenv-rehash,
 # then tell the shell to empty its command lookup cache.
 pyenv-rehash
-echo "hash -r"
+
+case "$shell" in
+fish )
+  or='; or'
+  ;;
+* )
+  or='||'
+  ;;
+esac
+
+echo "hash -r 2>/dev/null $or true"
diff --git a/libexec/pyenv-sh-shell b/libexec/pyenv-sh-shell
index 245c2687..857359a4 100755
--- a/libexec/pyenv-sh-shell
+++ b/libexec/pyenv-sh-shell
@@ -24,6 +24,7 @@ if [ "$1" = "--complete" ]; then
 fi
 
 versions=("$@")
+shell="$(basename "$SHELL")"
 
 if [ -z "$versions" ]; then
   if [ -z "$PYENV_VERSION" ]; then
@@ -36,7 +37,14 @@ if [ -z "$versions" ]; then
 fi
 
 if [ "$versions" = "--unset" ]; then
-  echo "unset PYENV_VERSION"
+  case "$shell" in
+  fish )
+    echo "set -e PYENV_VERSION"
+    ;;
+  * )
+    echo "unset PYENV_VERSION"
+    ;;
+  esac
   exit
 fi
 
@@ -45,8 +53,15 @@ if pyenv-prefix "${versions[@]}" >/dev/null; then
   OLDIFS="$IFS"
   IFS=: PYENV_VERSION="${versions[*]}"
   IFS="$OLDIFS"
-  echo "export PYENV_VERSION=\"${PYENV_VERSION}\""
+  case "$shell" in
+  fish )
+    echo "setenv PYENV_VERSION \"${PYENV_VERSION}\""
+    ;;
+  * )
+    echo "export PYENV_VERSION=\"${PYENV_VERSION}\""
+    ;;
+  esac
 else
-  echo "return 1"
+  echo "false"
   exit 1
 fi