# Cd built-in

The cd built-in changes the working directory.

## Syntax

- `cd [-L|-P [-e]] [directory]`

## Description

The cd built-in changes the working directory to the directory specified by the operand.

The pathname of the new working directory is assigned to the `PWD` variable, whose previous value is again assigned to the `OLDPWD` variable. The new `PWD` value will not contain any `.` or `..` components except when the shell is in the POSIXly-correct mode and the new pathname begins with `/..`.

If directory is a relative path that does not start with ‘.’ or ‘..’, paths in the `CDPATH` variable are searched to find a new working directory. The search is done in a manner similar to the last step of command search, but a directory is sought instead of an executable regular file. If a new working directory was found from `CDPATH`, its pathname is printed to the standard output. If no applicable directory was found in the search, directory is simply treated as a pathname relative to the current working directory.

If the working directory was successfully changed, the value of the `YASH_AFTER_CD` variable is executed as a command unless the shell is in the POSIXly-correct mode. If the variable is an array, its values are executed iteratively (cf. eval built-in).

## Options

`-L`
`--logical`

  Symbolic links in the pathname of the new working directory are not resolved. The new value of the `PWD` may include pathname components that are symbolic links.

`-P`
`--physical`

  Symbolic links in the pathname of the new working directory are resolved. The new value of the `PWD` variable never includes pathname components that are symbolic links.

`-e`
`--ensure-pwd`

  This option must be specified with `-P` (`--physical`). If this option is specified and if the absolute pathname of the new working directory cannot be obtained after successfully changing the working directory, the exit status is 1. If this option is not specified, the exit status is 0 in such a case.

`--default-directory=directory`

  If this option is specified and the directory operand is omitted, the argument to this option is used for the directory operand. If the directory operand is specified, this option is ignored.

The `-L` (`--logical`) and `-P` (`--physical`) options are mutually exclusive: only the last specified one is effective. If neither is specified, `-L` is assumed.

## Operands

directory

  The pathname of the new working directory.

  If directory is a single hyphen (‘-’), the value of the `OLDPWD` variable is assumed for the new directory pathname, which is printed to the standard output.

  If directory is omitted, the working directory is changed to the directory specified by the `--default-directory=…` option. If that option is not specified either, the default is the home directory.

## Exit status

- If the working directory is successfully changed, the exit status is 0, except in the following cases the exit status is 1:

  - The `PWD` or `OLDPWD` variable cannot be updated because the variable is read-only.

  - The `-P` and `-e` options are effective and the `PWD` variable cannot be updated because the absolute pathname of the new working directory cannot be obtained.

- If the working directory cannot be changed because of an error in the underlying `chdir` system call, the exit status is 2.

- If the `-L` option is effective and the new directory pathname cannot be canonicalized because of a `..` component referring to a non-existent directory, the exit status is 3.

- If directory cannot be processed because of an unset or empty `HOME` or `OLDPWD`, the exit status is 4.

- If the command arguments are invalid or if an empty operand is supplied for directory, the exit status is 5.

If and only if the exit status is 2 or larger, the working directory is not changed.

## Notes

The cd built-in is a mandatory built-in.

The POSIX standard does not define the use of the `YASH_AFTER_CD` variable or the `--default-directory=…` option.

The exit status of the commands in the `YASH_AFTER_CD` variable does not affect that of the cd built-in.