如何在我的mac上正确设置我的git $ PATH（我做了，但需要了解它是如何工作的）？

Question

I installed GIT from the site on my mac, but git --version gave me the old installation (I guess xcode installation). So I solved doing this:

• create a ~/.bash_profile file

• write:

  export PATH=/usr/local/bin:$PATH

• restart the terminal

Though, I think there's something in my configuration I could better setup.

My current echo $PATH

/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/git/bin

So IT WORKS, but it's quite a mess, since I've got 2 /usr/local/bin AND an /usr/local/git/bin

Also, I cannot understand WHY now it works, since /usr/local/bin only contains bbedit commands:

• bbdiff
• bbedit
• bbfind

---

I do not know very well all the path-config files and the real order they are read. I only know a few unix commands.. My current files in ~/ are:

~/.profile:

if [ -f ~/.bashrc ];
then
    source ~/.bashrc
fi

~/bashrc:

. ~/bin/dotfiles/bashrc

then in . ~/bin/dotfiles/bashrc

. ~/bin/dotfiles/bash/env
. ~/bin/dotfiles/bash/config
. ~/bin/dotfiles/bash/aliases

and in . ~/bin/dotfiles/bash/env:

export PATH=/usr/local/bin:/opt/local/bin:/opt/local/sbin:$PATH

. ~/bin/dotfiles/bash/config is just empty

and . ~/bin/dotfiles/bash/aliases contains some alias commad.

Anyway, it SHOULD have read ~/bin/dotfiles/bash/env, but it doesn't. Or it reads it only after /etc/paths

~/.bash_profile is read first instead.

My current /etc/paths content:

/usr/bin
/bin
/usr/sbin
/sbin
/usr/local/bin

---

Can anyone explain me the these mechanics? :P Or Maybe I should post this question to some Unix group?

Answer 1

When you type any command on a *NIX shell, the shell tries to resolve that command using the $PATH . Say your path is /usr/bin:/usr/local/bin , then this happens:

$ foo
- Does /usr/bin/foo exist? No.
- Does /usr/local/bin/foo exist? No.
- Does foo exist in the current working directory?

In other words, it looks at each $PATH element in turn and tries to find the executable you asked for there. This is the reason the typical configure - make - make install procedure starts with a ./configure , to make explicit that you want to run the configure executable in the current directory , not some system-wide command.

To figure out which foo it's actually choosing in the end, run:

$ which foo

You can run any command explicitly by providing its full path:

$ /usr/local/bin/foo  # overrides /usr/bin/foo, should it exist

The export PATH=...:$PATH directive in your initialization scripts is simply prepending certain paths to your path, allowing you to override the precedence in which order commands are resolved. It's not ideal that /usr/local/bin is in there twice, but it's not really a problem either. You should take care not to let your path grow too long, since that may result in a lot of lookups for every command and may screw with your head, too.

Answer 2

有关bash配置文件的加载顺序的全面演练，请参阅此内容 。