type

Dit deel is nog niet vertaald. Je ziet de Engelse tekst.

Wat het doet

type is built into Bash. It answers the question "if I type this name, what will run?" It knows about aliases, functions and shell built-ins, which a tool like which cannot see.

Use it when a command does something you did not expect: maybe an alias with the same name hides the real program, or a script found a different program in $PATH.

The help text is in Bash itself: help type.

Zo schrijf je het

type [-afptP] NAME [NAME ...]

Opties 5

Meest gebruikt

-t: Print only one word: alias, keyword, function, builtin, file, or nothing if not found.
-a: Show every place where NAME is found: alias, function, built-in and every file in $PATH.
-p: Print the path of the file that would run, but only when NAME is a file (nothing for an alias or built-in).
-P: Search $PATH for a file, even when NAME is also an alias, function or built-in.
-f: Do not look for shell functions.

Voorbeelden 11

$ als gewone gebruiker# als root (of met sudo)

1Find out what a name is
```
$type ls
ls is aliased to `ls --color=auto'
```
On RHEL, ls is an alias that adds colors.
2Show every match, in the order Bash uses them
```
$type -a ls
ls is aliased to `ls --color=auto'
ls is /usr/bin/ls
```
The first line wins. The program file is only used when there is no alias.
3Get one word for a script
```
$type -t cd
builtin
```
Possible answers: alias, keyword, function, builtin, file.
4Check if a command is installed before you use it
```
$if type -P jq >/dev/null; then echo "jq found"; else echo "please install jq"; fi
```
type -P returns an error code when the program is not in $PATH. Good for install checks.
5See if a name is a shell keyword
```
$type if
if is a shell keyword
```
Keywords like if, for and [[ are part of the Bash language.
6Find the real program behind an alias
```
$type -P grep
/usr/bin/grep
```
Shows the file even though grep is also an alias.
7Look at a shell function
```
$type my_backup
```
If my_backup is a function, Bash prints its full code. Useful to debug functions from ~/.bashrc.
8Check several names at once
```
$type -t python3 docker podman kubectl
file
file
```
Names that are not found print nothing in -t mode. Here only two of four are installed.
9Find out why an old version of a tool runs
```
$type -a terraform
terraform is /usr/local/bin/terraform
terraform is /usr/bin/terraform
```
Two copies are installed. The first one in $PATH wins; remove or rename the old one.
10Detect a hidden alias in a security review
```
$type sudo
```
If an attacker added alias sudo=... to a .bashrc, type shows it. Real sudo is /usr/bin/sudo.
11Use type in a script to require a tool
```
$type -P rsync >/dev/null || { echo "rsync is missing" >&2; exit 1; }
```
Stops the script early with a clear message.

Let op

type is a Bash built-in. It does not exist as a program file, so sudo type does not work.
which does not know functions and built-ins (it only searches files), so the two can give different answers.

Tips om te onthouden

type = what runs, type -a = everything that could run, type -P = only the file.
Remember the order Bash uses: alias → keyword → function → built-in → file in $PATH.

`type`

Wat het doet

Zo schrijf je het

Opties 5

Voorbeelden 11

1Find out what a name is

2Show every match, in the order Bash uses them

3Get one word for a script

4Check if a command is installed before you use it

5See if a name is a shell keyword

6Find the real program behind an alias

7Look at a shell function

8Check several names at once

9Find out why an old version of a tool runs

10Detect a hidden alias in a security review

11Use type in a script to require a tool

Let op

Tips om te onthouden

Volledige handleiding

Wat het doet

Zo schrijf je het

Opties 5

Voorbeelden 11

1Find out what a name is

2Show every match, in the order Bash uses them

3Get one word for a script

4Check if a command is installed before you use it

5See if a name is a shell keyword

6Find the real program behind an alias

7Look at a shell function

8Check several names at once

9Find out why an old version of a tool runs

10Detect a hidden alias in a security review

11Use type in a script to require a tool

Let op

Tips om te onthouden

Verwante commando's

Gebruikt in deze lessen

Gebruikt in deze labs

Volledige handleiding

`type`