ENH only make aliases when binaries exists

dot_config/zsh/dot_zshrc.tmpl

@@ -192,11 +192,17 @@ precmd () { echo -ne "\033]0;urxvt: ${PWD}\007" }
 
 alias als='alias | grep'
 alias hs='history 1 | grep'
-alias ls='ls --color'
 
 alias grep='grep --color=auto'
 alias sudo='sudo '
+
+if [ -e /bin/colordiff ]; then
     alias diff=colordiff
+else
+    alias diff='diff --color'
+fi
+
+alias ls='ls --color'
 
 if [ -e /bin/exa ]; then
     alias ll='exa -alhg --group-directories-first'
@@ -246,6 +252,7 @@ alias scus="systemctl --user start"
 alias scut="systemctl --user stop"
 alias scur="systemctl --user restart"
 
+if [ -e /bin/git ]; then
     alias g='git'
     alias gcl='git clone'
     alias ga='git add'
@@ -273,12 +280,15 @@ alias gw="git whatchanged"
     alias gt="git tag"
     alias gnew="git log HEAD@{1}..HEAD@{0}"
     alias ggui="git gui"
+fi
 
+if [ -e /bin/chezmoi ]; then
     alias cze="chezmoi edit"
     alias czea="chezmoi edit --apply"
     alias czd="chezmoi diff"
     alias cza="chezmoi add"
     alias czc="chezmoi cd"
+fi
 
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 ## Manly Colors