Команда cd: Переход по директориям в различных операционных системах

Computer command in various operating systems

The command, also known as (change directory), is a command line shell command used to change the current working directory in various operating systems. It can be used in shell scripts and batch files.

The command has been implemented in operating systems such as Unix, DOS, IBM OS/2, MetaComCo TRIPOS, AmigaOS (where if a bare path is given, cd is implied), Microsoft Windows, ReactOS, and Linux. On MS DOS, it is available in versions 2 and later. DR DOS 6.0 also includes an implementation of the and commands. The command is also available in the open source MS DOS emulator DOSBox and in the EFI shell. It is named in HP MPE/iX. The command is analogous to the Stratus OpenVOS command. is frequently included built directly into a command line interpreter. This is the case in most of the Unix shells (Bourne shell, tcsh, bash, etc. ), cmd. exe on Microsoft Windows NT/2000+ and Windows PowerShell on Windows 7+ and COMMAND. COM on DOS/ Microsoft Windows 3. x 9x/ME. The system call that effects the command in most operating systems is that is defined by POSIX. Command line shells on Windows usually use the Windows API to change the current working directory, whereas on Unix systems calls the POSIX C function. This means that when the command is executed, no new process is created to migrate to the other directory as is the case with other commands such as ls. Instead, the shell itself executes this command. This is because, when a new process is created, child process inherits the directory in which the parent process was created. If the command inherits the parent process' directory, then the objective of the command cd will never be achieved. Windows PowerShell, Microsoft's object oriented command line shell and scripting language, executes the command (cmdlet) within the shell's process. However, since PowerShell is based on the NET Framework and has a different architecture than previous shells, all of PowerShell's cmdlets like , etc. run in the shell's process. Of course, this is not true for legacy commands which still run in a separate process.

by itself or will always put the user in their home directory. will leave the user in the same directory they are currently in (i. e. the current directory won't change). This can be useful if the user's shell's internal code can't deal with the directory they are in being recreated; running will place their shell in the recreated directory. cd ~username will put the user in the username's home directory. (without a ) will put the user in a subdirectory; for example, if they are in , typing will put them in , while puts them in will move the user up one directory. So, if they are , moves them to , while moves them to (i. e. up two levels). The user can use this indirection to access subdirectories too. So, from , they can use to go to
will switch the user to the previous directory. For example, if they are in , and go to , they can type to go back to The user can use this to toggle back and forth between two directories without pushd and popd.

no attributes print the full path of the current directory. Print the final directory stack, just like dirs. Entries are wrapped before they reach the edge of the screen. entries are printed one per line, preceded by their stack positions. (DOS and Windows only) returns to the root dir. Consequently, command always takes the user to the named subdirectory on the root directory, regardless of where they are located when the command is issued.