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Syntax

cd [directory]
cd -
cd

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Description

The cd command changes the current working directory within Nash’s virtual filesystem. When you change directories, Nash automatically updates the $PWD environment variable to reflect the new location and saves the previous directory in $OLDPWD.
All directory changes happen within Nash’s Virtual Filesystem (VFS). Host directories are only accessible through explicit mount bindings using --bind or --bind-ro flags when starting Nash.

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Arguments

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directory
string
The target directory to change to. Can be an absolute path (starting with /) or relative path.Special values:
  • No argument: Changes to $HOME directory (default: /home/user)
  • -: Changes to the previous directory stored in $OLDPWD

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Behavior

  1. No arguments - Navigates to the user’s home directory from the $HOME environment variable
  2. Relative paths - Resolved relative to the current working directory ($PWD)
  3. Absolute paths - Navigate directly to the specified path
  4. cd - - Toggle to the previous working directory using $OLDPWD
  5. Environment updates - Automatically sets $PWD to new directory and $OLDPWD to previous directory

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Examples

user@nash:/home/user$ cd /etc
user@nash:/etc$ pwd
/etc

user@nash:/home/user$ mkdir projects
user@nash:/home/user$ cd projects
user@nash:/home/user/projects$ pwd
/home/user/projects

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Go back to previous directory

user@nash:/home/user$ cd /tmp
user@nash:/tmp$ cd /etc
user@nash:/etc$ cd -
user@nash:/tmp$ pwd
/tmp

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Return to home directory

user@nash:/etc$ cd
user@nash:/home/user$ pwd
/home/user

user@nash:/$ cd $HOME/Documents
user@nash:/home/user/Documents$ pwd
/home/user/Documents

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Use with subshells

user@nash:/home/user$ pwd
/home/user
user@nash:/home/user$ (cd /tmp && pwd)
/tmp
user@nash:/home/user$ pwd
/home/user
Changes made inside a subshell ( ) do not affect the parent shell’s working directory.

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Error Handling

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Directory does not exist

user@nash:/home/user$ cd nonexistent
cd: not a directory: nonexistent

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Not a directory (file path provided)

user@nash:/home/user$ touch file.txt
user@nash:/home/user$ cd file.txt
cd: not a directory: file.txt

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No previous directory

user@nash:/home/user$ unset OLDPWD
user@nash:/home/user$ cd -
user@nash:/$ pwd
/
If $OLDPWD is not set, cd - defaults to the root directory /.

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VFS Integration

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Working with mounted directories

When starting Nash with host directory mounts, you can navigate into them normally: 
# Start Nash with a mount
$ nash --bind ./myproject:/project

user@nash:/home/user$ cd /project
user@nash:/project$ ls
# Shows files from host ./myproject directory

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Read-only mounts

You can cd into read-only mounted directories without any restrictions: 
$ nash --bind-ro ./config:/config

user@nash:/home/user$ cd /config
user@nash:/config$ pwd
/config
user@nash:/config$ cat settings.json
# Read operations work normally

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Environment Variables

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$PWD
string
Automatically updated to the new current working directory after each successful cd command.
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$OLDPWD
string
Automatically updated to store the previous working directory before changing to a new one. Used by cd -.
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$HOME
string
Used as the target directory when cd is called without arguments. Default: /home/<username>
  • pwd - Print the current working directory
  • mkdir - Create new directories
  • ls - List directory contents
  • tree - Display directory structure as a tree

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Implementation Details

The cd command is implemented in /home/daytona/workspace/source/src/builtins/cd.rs:9-41. Key implementation notes:
  • Validates that the target path exists and is a directory before changing
  • Uses VfsPath::join() to resolve relative paths against the current directory
  • Always updates both $PWD and $OLDPWD environment variables
  • Falls back to /home/user if $HOME is not defined
  • Falls back to / if $OLDPWD is not set when using cd -

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