$ touch i e o

$ ls -lrh
total 0
-rw-r--r-- 1 root root 0 May 23 08:24 o
-rw-r--r-- 1 root root 0 May 23 08:24 i
-rw-r--r-- 1 root root 0 May 23 08:24 e


$ echo [offline]
e i o

$ echo [online]
e i o

$ echo [error]
e o

$ echo [soap]
o

$ rm -f e i o

$ ls
$ echo [offline]
[offline]

$ echo [online]
[online]

$ echo [error]
[error]

$ echo [soap]
[soap]