怎么替换字符串中的特定字段

windboys

象$PATH这样的字符串，如果我希望其中的某个路径被换掉，而不是保留在其中，我该怎么做？
ex. PATH=usr/loal/:/home/aaa:/... ->ATH=usr/loal/:/home/bbb:/...

猫搂鱼睡觉

debian:~$ a=PATH=usr/loal/:/home/aaa:/
debian:~$ echo $a
PATH=usr/loal/:/home/aaa:/
debian:~$ echo $a|sed 's/aaa/bbb/'
PATH=usr/loal/:/home/bbb:/

windboys

Post by 猫搂鱼睡觉
debian:~$ a=PATH=usr/loal/:/home/aaa:/
debian:~$ echo $a
PATH=usr/loal/:/home/aaa:/
debian:~$ echo $a|sed 's/aaa/bbb/'
PATH=usr/loal/:/home/bbb:/

Thank you!


sed ///