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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)
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.
cd — change the working directory
cd [−L|−P] [directory]
cd −
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).
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.
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.
Not used.
None.
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.
Default.
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.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 The directory was successfully changed.
>0 An error occurred.
The working directory shall remain unchanged.
The following sections are informative.
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.
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 -
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.
None.
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)
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)
Pages that refer to this page: pwd(1p), sh(1p)