PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

CD(1P)                    POSIX Programmer's Manual                   CD(1P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       cd — change the working directory

SYNOPSIS         top

       cd [−L|−P] [directory]

       cd −

DESCRIPTION         top

       The cd utility shall change the working directory of the current
       shell execution environment (see Section 2.12, Shell Execution
       Environment) by executing the following steps in sequence. (In the
       following steps, the symbol curpath represents an intermediate value
       used to simplify the description of the algorithm used by cd.  There
       is no requirement that curpath be made visible to the application.)

        1. If no directory operand is given and the HOME environment
           variable is empty or undefined, the default behavior is
           implementation-defined and no further steps shall be taken.

        2. If no directory operand is given and the HOME environment
           variable is set to a non-empty value, the cd utility shall behave
           as if the directory named in the HOME environment variable was
           specified as the directory operand.

        3. If the directory operand begins with a <slash> character, set
           curpath to the operand and proceed to step 7.

        4. If the first component of the directory operand is dot or dot-
           dot, proceed to step 6.

        5. Starting with the first pathname in the <colon>-separated
           pathnames of CDPATH (see the ENVIRONMENT VARIABLES section) if
           the pathname is non-null, test if the concatenation of that
           pathname, a <slash> character if that pathname did not end with a
           <slash> character, and the directory operand names a directory.
           If the pathname is null, test if the concatenation of dot, a
           <slash> character, and the operand names a directory. In either
           case, if the resulting string names an existing directory, set
           curpath to that string and proceed to step 7. Otherwise, repeat
           this step with the next pathname in CDPATH until all pathnames
           have been tested.

        6. Set curpath to the directory operand.

        7. If the −P option is in effect, proceed to step 10. If curpath
           does not begin with a <slash> character, set curpath to the
           string formed by the concatenation of the value of PWD, a <slash>
           character if the value of PWD did not end with a <slash>
           character, and curpath.

        8. The curpath value shall then be converted to canonical form as
           follows, considering each component from beginning to end, in
           sequence:

            a. Dot components and any <slash> characters that separate them
               from the next component shall be deleted.

            b. For each dot-dot component, if there is a preceding component
               and it is neither root nor dot-dot, then:

                i.  If the preceding component does not refer (in the
                    context of pathname resolution with symbolic links
                    followed) to a directory, then the cd utility shall
                    display an appropriate error message and no further
                    steps shall be taken.

               ii.  The preceding component, all <slash> characters
                    separating the preceding component from dot-dot, dot-
                    dot, and all <slash> characters separating dot-dot from
                    the following component (if any) shall be deleted.

            c. An implementation may further simplify curpath by removing
               any trailing <slash> characters that are not also leading
               <slash> characters, replacing multiple non-leading
               consecutive <slash> characters with a single <slash>, and
               replacing three or more leading <slash> characters with a
               single <slash>.  If, as a result of this canonicalization,
               the curpath variable is null, no further steps shall be
               taken.

        9. If curpath is longer than {PATH_MAX} bytes (including the
           terminating null) and the directory operand was not longer than
           {PATH_MAX} bytes (including the terminating null), then curpath
           shall be converted from an absolute pathname to an equivalent
           relative pathname if possible. This conversion shall always be
           considered possible if the value of PWD, with a trailing <slash>
           added if it does not already have one, is an initial substring of
           curpath.  Whether or not it is considered possible under other
           circumstances is unspecified. Implementations may also apply this
           conversion if curpath is not longer than {PATH_MAX} bytes or the
           directory operand was longer than {PATH_MAX} bytes.

       10. The cd utility shall then perform actions equivalent to the
           chdir() function called with curpath as the path argument. If
           these actions fail for any reason, the cd utility shall display
           an appropriate error message and the remainder of this step shall
           not be executed. If the −P option is not in effect, the PWD
           environment variable shall be set to the value that curpath had
           on entry to step 9 (i.e., before conversion to a relative
           pathname). If the −P option is in effect, the PWD environment
           variable shall be set to the string that would be output by pwd
           −P.  If there is insufficient permission on the new directory, or
           on any parent of that directory, to determine the current working
           directory, the value of the PWD environment variable is
           unspecified.

       If, during the execution of the above steps, the PWD environment
       variable is set, the OLDPWD environment variable shall also be set to
       the value of the old working directory (that is the current working
       directory immediately prior to the call to cd).

OPTIONS         top

       The cd utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported by the implementation:

       −L        Handle the operand dot-dot logically; symbolic link
                 components shall not be resolved before dot-dot components
                 are processed (see steps 8.  and 9. in the DESCRIPTION).

       −P        Handle the operand dot-dot physically; symbolic link
                 components shall be resolved before dot-dot components are
                 processed (see step 7. in the DESCRIPTION).

       If both −L and −P options are specified, the last of these options
       shall be used and all others ignored. If neither −L nor −P is
       specified, the operand shall be handled dot-dot logically; see the
       DESCRIPTION.

OPERANDS         top

       The following operands shall be supported:

       directory An absolute or relative pathname of the directory that
                 shall become the new working directory. The interpretation
                 of a relative pathname by cd depends on the −L option and
                 the CDPATH and PWD environment variables. If directory is
                 an empty string, the results are unspecified.

       −         When a <hyphen> is used as the operand, this shall be
                 equivalent to the command:

                     cd "$OLDPWD" && pwd

                 which changes to the previous working directory and then
                 writes its name.

STDIN         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of cd:

       CDPATH    A <colon>-separated list of pathnames that refer to
                 directories. The cd utility shall use this list in its
                 attempt to change the directory, as described in the
                 DESCRIPTION. An empty string in place of a directory
                 pathname represents the current directory. If CDPATH is not
                 set, it shall be treated as if it were an empty string.

       HOME      The name of the directory, used when no directory operand
                 is specified.

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale
                 categories.)

       LC_ALL    If set to a non-empty string value, override the values of
                 all the other internationalization variables.

       LC_CTYPE  Determine the locale for the interpretation of sequences of
                 bytes of text data as characters (for example, single-byte
                 as opposed to multi-byte characters in arguments).

       LC_MESSAGES
                 Determine the locale that should be used to affect the
                 format and contents of diagnostic messages written to
                 standard error.

       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.

       OLDPWD    A pathname of the previous working directory, used by cd .

       PWD       This variable shall be set as specified in the DESCRIPTION.
                 If an application sets or unsets the value of PWD, the
                 behavior of cd is unspecified.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       If a non-empty directory name from CDPATH is used, or if cd is
       used, an absolute pathname of the new working directory shall be
       written to the standard output as follows:

           "%s\n", <new directory>

       Otherwise, there shall be no output.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    The directory was successfully changed.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       The working directory shall remain unchanged.

       The following sections are informative.

APPLICATION USAGE         top

       Since cd affects the current shell execution environment, it is
       always provided as a shell regular built-in. If it is called in a
       subshell or separate utility execution environment, such as one of
       the following:

           (cd /tmp)
           nohup cd
           find . −exec cd {} \;

       it does not affect the working directory of the caller's environment.

       The user must have execute (search) permission in directory in order
       to change to it.

EXAMPLES         top

       The following template can be used to perform processing in the
       directory specified by location and end up in the current working
       directory in use before the first cd command was issued:

           cd location
           if [ $? -ne 0 ]
           then
               print error message
               exit 1
           fi
           ... do whatever is desired as long as the OLDPWD environment variable
               is not modified
           cd -

RATIONALE         top

       The use of the CDPATH was introduced in the System V shell. Its use
       is analogous to the use of the PATH variable in the shell. The BSD C
       shell used a shell parameter cdpath for this purpose.

       A common extension when HOME is undefined is to get the login
       directory from the user database for the invoking user. This does not
       occur on System V implementations.

       Some historical shells, such as the KornShell, took special actions
       when the directory name contained a dot-dot component, selecting the
       logical parent of the directory, rather than the actual parent
       directory; that is, it moved up one level toward the '/' in the
       pathname, remembering what the user typed, rather than performing the
       equivalent of:

           chdir("..");

       In such a shell, the following commands would not necessarily produce
       equivalent output for all directories:

           cd .. && ls      ls ..

       This behavior is now the default. It is not consistent with the
       definition of dot-dot in most historical practice; that is, while
       this behavior has been optionally available in the KornShell, other
       shells have historically not supported this functionality. The
       logical pathname is stored in the PWD environment variable when the
       cd utility completes and this value is used to construct the next
       directory name if cd is invoked with the −L option.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 2.12, Shell Execution Environment, pwd(1p)

       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1‐2008, chdir(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) In the event of any discrepancy between this version and
       the original IEEE and The Open Group Standard, the original IEEE and
       The Open Group Standard is the referee document. The original
       Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                              CD(1P)