linux 查看命令是不是內建命令(查看命令的位置) “type”

type [
-
aftpP]
name [
name .
.
.
]

      With no
options,
indicate how each
name would be interpreted if
used as a command name.




   If
the -
t option is used,
type prints a string which is one of alias,
keyword,
function,
builtin,
or
file if
name is an alias,
shell reserved word,
function,
builtin,
or
disk file,
respectively.
If
the name is not
found,
then nothing is printed,
and
an exit
status of false
is returned.




    If
the -
p option is used,
type either returns the name of the disk file that would be executed if
name were specified as a command name,
or
nothing if
‘‘type -
t name’’ would not
return
file.
The -
P option forces a PATH search for
each
name,
even if
‘‘type -
t name’’ would not
return
file.
If
a command is hashed,
-
p and
-
P print
the hashed value,
not
necessarily the file that appears first in PATH.





     If
the -
a option is used,
type prints all of the places that contain an executable named name.
This includes aliases and
functions,
if
and
only if
the -
p option is not
also used.
The table of hashed commands is not
consulted when using -
a.
The -
f option suppresses shell function lookup,
as with the command builtin.




    type returns true
if
any of the arguments are found,
false
if
none are found.



 

 

 

 

eg:

[root@localhost Desktop]# type -a ls
ls is aliased to `ls --color=tty'
ls is /bin/ls
[root@localhost Desktop]# type -a type
type is a shell builtin