字符串 a/b/c/def
比如要替换字符串 a/b/c 为aaa

# 未加转义符

[root@localhost ~]# sed -i 's/a/b/c/aaa/g' test.txt
sed: -e expression #1, char 7: unknown option to `s'

不加转义则报错

# 加转义

[root@localhost ~]# sed -i 's/a\/b\/c/aaa/g' test.txt
[root@localhost ~]# cat test.txt
aaa/def

# 加转义符不美观，可以换个分隔符来实现

[root@localhost ~]# cat test.txt
a/b/c/def
[root@localhost ~]# sed -i 's#a/b/c#aaa#g' test.txt
[root@localhost ~]# cat test.txt
aaa/def