type Command in Linux
The type command in Linux displays information about the command type. It checks how the shell interprets a command name, whether it is an alias, a shell function, a shell built-in, or a binary executable. When a command is entered, the shell searches in a specific order: it first looks for an alias, then a function, then a built-in, and finally a binary file stored in the filesystem.
Table of Contents
Here is a comprehensive guide to the options available with the type command −
Syntax of type Command
The syntax of the Linux type command is as follows −
type [options] [commandâ¦]
In the above syntax, the [options] is an optional argument used to specify options that modify how the type command behaves. The [command...] argument is the name of the command (or multiple commands) that need to be checked.
Options of type Command
The options of the type command in Linux are listed below −
| Option | Description |
|---|---|
| -a | Show all locations of a command (aliases, builtins, functions) unless -p is also used. |
| -f | Skip shell function lookup. |
| -P | Force a PATH search and show the disk file even if an alias, a builtin, or a function exists. |
| -p | Return the disk file name that would be executed, or nothing if not a file. |
| -t | Output one word: alias, keyword, function, builtin, file, or empty if not found. |
Examples of type Command in Linux
This section demonstrates how to use the type command in Linux with examples −
Checking the Command Type
To check the type of a command, use the type command followed by the command name. For example, to check the type of cat, use the following command −
type cat
Similarly, to check the command type of if, use the following command −
type if
There are different command types. A list of command types is given below −
| Command Type | Meaning |
|---|---|
| alias | A shortcut or custom name for another command (example: alias ll='ls -la'). |
| keyword | A shell reserved word, part of the shell syntax (example: if, for, then, while). |
| function | A user-defined shell function (a block of shell commands grouped together). |
| builtin | A command built directly into the shell (example; cd, echo, type itself). |
| file | A standalone executable binary or script found in the filesystem (example: /bin/ls). |
| (empty) | Returned when the name is not found, it does not exist in any form. |
Checking the Command Type of Multiple Commands
Execute the following command to check the command types of multiple commands −
type cat echo
Listing all Possible Locations of a Command
To list all possible locations of a command, including both alias and binary, use the -a option −
type -a ls
Printing only the Type
To display the type of the command without the additional details, use the -t option −
type -t ls
Similarly, types of the echo and cat commands are shown in the following image −
Displaying the Real Executable
To force disk file lookup, ignoring the alias and built-ins, use the -P option with the type command −
type -P cat
Conclusion
The type command in Linux is useful for determining how the shell interprets a command, whether it is an alias, function, built-in, or executable file. It follows a search order, first checking for aliases, then functions, built-ins, and finally executable files. The command offers several options to customize its behavior, such as displaying all possible locations of a command, skipping function lookup, or forcing a path search for executable files.