Make sure that /usr/local/bin is in your $PATH.

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

ps:One note: you don’t need quotation marks here because it’s on the right hand side of an assignment, but in general, and especially on Macs with their tradition of spacy pathnames, expansions like $PATHshouldbedouble-quotedas"$PATH".

pps:不要乱搞权限，惨痛教训