我不能让expand_aliases在bash中生效.我尝试了很多不同的事情,没有任何作用.
这是简单的测试用例：
/bin/bash -c 'shopt -s expand_aliases; alias cdtmp="cd /tmp"; alias; cdtmp; pwd;'
并输出：
$/bin/bash -c 'shopt -s expand_aliases; alias cdtmp="cd /tmp"; alias; cdtmp; pwd;' alias cdtmp='cd /tmp' /bin/bash: cdtmp: command not found /home/user $/bin/bash --version GNU bash,version 3.2.25(1)-release (i686-redhat-linux-gnu) Copyright (C) 2005 Free Software Foundation,Inc.
(是的,我正在使用shopt而不是-O选项来bash,只是为了证明它已经完成了.)
有任何想法吗？
别名不可用于同一行或相同功能的定义.
从Bash手册页：
The rules concerning the definition and use of aliases are somewhat
confusing. Bash always reads at least one complete line of input
before executing any of the commands on that line. Aliases are
expanded when a command is read,not when it is executed. Therefore,an alias definition appearing on the same line as another command does
not take effect until the next line of input is read. The commands
following the alias definition on that line are not affected by the new
alias. This behavior is also an issue when functions are executed.
Aliases are expanded when a function definition is read,not when the
function is executed,because a function definition is itself a com‐
pound command. As a consequence,aliases defined in a function are not
available until after that function is executed. To be safe,always
put alias definitions on a separate line,and do not use alias in com‐
pound commands.
For almost every purpose,aliases are superseded by shell functions.
For almost every purpose,shell functions are preferred over aliases.
而不是[强调我的]最后一句.我认为别名是一个命令行的便利,而不是脚本中应该使用的东西(包括那些仅由bash -c一个线程组成的).
