Improve interactiveness checks (#3449)

* [bash] return instead of not executing an if-block, when non-interactive

This should keep the code more readable, be less error prone (accidentally doing
something outside the if-block and aligns the code with what’s already done for
zsh.

`0` is returned, because it shall not be considered an error when the script is
(accidentally) sourced from a non-interactive shell.

If executed as a script (rather than sourced), the results are not specified by
POSIX but depend on the shell, with bash giving an error in that case.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>

* [shell] exit immediately when called from non-interactive shell

The shell execution environment shouldn’t be modified at all, when called from a
non-interactive shell.

It shall be noted that the current check may become error prone for bash, namely
in case there should ever be a differentiation between `i` and `I` in the
special variable `-` and bash’s `nocasematch`-shell-option be used.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>

shell/completion.bash

@@ -9,7 +9,8 @@
 # - $FZF_COMPLETION_TRIGGER (default: '**')
 # - $FZF_COMPLETION_OPTS    (default: empty)
 
-if [[ $- =~ i ]]; then
+[[ $- =~ i ]] || return 0
+
 
 # To use custom commands instead of find, override _fzf_compgen_{path,dir}
 if ! declare -F _fzf_compgen_path > /dev/null; then
@@ -401,5 +402,3 @@ _fzf_setup_completion 'var'   export unset printenv
 _fzf_setup_completion 'alias' unalias
 _fzf_setup_completion 'host'  telnet
 _fzf_setup_completion 'proc'  kill
-
-fi

shell/completion.zsh

@@ -9,6 +9,9 @@
 # - $FZF_COMPLETION_TRIGGER (default: '**')
 # - $FZF_COMPLETION_OPTS    (default: empty)
 
+[[ -o interactive ]] || return 0
+
+
 # Both branches of the following `if` do the same thing -- define
 # __fzf_completion_options such that `eval $__fzf_completion_options` sets
 # all options to the same values they currently have. We'll do just that at
@@ -73,9 +76,6 @@ fi
 # `finally` in lesser languages. We use it to *always* restore user options.
 {
 
-# Bail out if not interactive shell.
-[[ -o interactive ]] || return 0
-
 # To use custom commands instead of find, override _fzf_compgen_{path,dir}
 if ! declare -f _fzf_compgen_path > /dev/null; then
   _fzf_compgen_path() {

shell/key-bindings.bash

@@ -11,6 +11,9 @@
 # - $FZF_ALT_C_COMMAND
 # - $FZF_ALT_C_OPTS
 
+[[ $- =~ i ]] || return 0
+
+
 # Key bindings
 # ------------
 __fzf_select__() {
@@ -27,8 +30,6 @@ __fzf_select__() {
     done
 }
 
-if [[ $- =~ i ]]; then
-
 __fzfcmd() {
   [[ -n "${TMUX_PANE-}" ]] && { [[ "${FZF_TMUX:-0}" != 0 ]] || [[ -n "${FZF_TMUX_OPTS-}" ]]; } &&
     echo "fzf-tmux ${FZF_TMUX_OPTS:--d${FZF_TMUX_HEIGHT:-40%}} -- " || echo "fzf"
@@ -130,5 +131,3 @@ fi
 bind -m emacs-standard '"\ec": " \C-b\C-k \C-u`__fzf_cd__`\e\C-e\er\C-m\C-y\C-h\e \C-y\ey\C-x\C-x\C-d"'
 bind -m vi-command '"\ec": "\C-z\ec\C-z"'
 bind -m vi-insert '"\ec": "\C-z\ec\C-z"'
-
-fi

shell/key-bindings.zsh

@@ -11,6 +11,9 @@
 # - $FZF_ALT_C_COMMAND
 # - $FZF_ALT_C_OPTS
 
+[[ -o interactive ]] || return 0
+
+
 # Key bindings
 # ------------
 
@@ -36,8 +39,6 @@ fi
 
 {
 
-[[ -o interactive ]] || return 0
-
 # CTRL-T - Paste the selected file path(s) into the command line
 __fsel() {
   local cmd="${FZF_CTRL_T_COMMAND:-"command find -L . -mindepth 1 \\( -path '*/.*' -o -fstype 'sysfs' -o -fstype 'devfs' -o -fstype 'devtmpfs' -o -fstype 'proc' \\) -prune \