Provided by: xd_3.29.00-2_amd64 
NAME
xd - eXtra fast Directory changer
SYNOPSIS
xd [OPTIONS] arguments
DESCRIPTION
The program xd is used to perform eXtra fast Directory changes. Usually to change a directory the user is
required to enter a command like, e.g., cd /usr/local/bin, possibly with the aid of shell completion. In
many cases this is a tedious task: shell completion shows all entries, including files, when we’re only
interested in directories and the full specification of our intented directory may eventually require
many keyboard actions.
Xd was designed a long time ago (in the early 90s) to reduce the effort of changing directories. Often
we’re well aware to which directory we want to change, and it’s easy to produce the initial directory
characters of that directory. E.g., if the intent is to cd to /usr/local/bin, it’s quite easy to produce
the letters ulb.
Xd capitalizes on this capability. By providing the initial directory characters of directories xd
determines the proper expansion allowing you to change directories fast. So, entering the command xd ulb
results in the expansion /usr/local/bin.
Often life is not that easy. Often there are multiple expansions from a given set of initial characters.
E.g., when entering xd ulb xd may find several alternatives. E.g.,
1: /usr/lib/base-config
2: /usr/lib/bonobo
3: /usr/lib/bonobo-activation
4: /usr/local/bin
If these are the alternatives, this is exactly what xd will show you. Then, by simply pressing the 3 key
(no Enter key required) xd will produce the required /usr/local/bin.
Commands to xd can be specified so as to fine-tune xd’s behavior:
o By default (as specified by the configuration file, see below) expansions may start at the user’s
home directory or at the system’s root directory.
o Initial character /: If the first character of the command is / then all expansions are performed
from the system’s root directory. E.g., xd /t results in /tmp but not in /home/user/tmp.
o Initial character .: If the first character of the command is . then by default all expansions are
performed from the user’s home directory. E.g., xd .t results in /home/user/tmp but not in /tmp.
The home directory recognition character can be altered using the --homedir-char option, see below
(section OPTIONS).
o Initial character 0: If the first character of the command is 0, then all expansions start at the
current working directory. In fact, this is a specialization of the following, more general form:
o Initial character 1..9: If the first character of the command is a digit between 1 and 9 then all
expansions start at that parent directory level of the current working directory (up to the
system’s root directory). E.g., if the current working directory is /usr/share/doc then xd 2lb
will offer the alternative /usr/local/bin: two steps up, then look for directories starting with l
and therein directories starting with b.
o Separators (space, and the forward slash (`/’)): sometimes it is clear that there are many
alternatives and the intention is to reduce that number. By using separators subsequently nested
directories must start with the characters between the separators. E.g., xd u l bi never produces
the alternative /usr/lib/base-config anymore, since base-config does not start with bi. In this
case only /usr/local/bin is produced. When used as initial character in a pattern the forward
slash always indicates the root-directory.
o Search patterns may contain dots (like .s). In such cases the dot represents hidden directories.
However, xd usually also finds patterns containing /./, as the current directory matches the dot.
Such patterns are considered spurious and are not reported.
If there’s only one solution, Xd writes that directory to its standard output stream. If there are
multiple solutions, then a list of at most 62 alternatives (10 for the numbers 0..9, 26 for the letters
a..z and 26 for the letters A..Z) is written to the standard error stream from which the user may select
an alternative by simply pressing the key associated with the selection of choice. If no selection is
requested any other key may be pressed (e.g., the space bar or the Enter key). If there is no solutioon
xd writes the text No Solutions to the standard error stream.
When xd is given at least one argument, all its output is sent to the standard error stream, but for the
selected directory name which is written to the standard output stream. If no selection is made or if the
selection process is aborted a single dot is written to the standard output stream. Usually xd will be
called by a shell alias, providing the cd command with xd’s output (see below at the SHELL SCRIPTS
section) executing cd `xd $*`. The default dot produced by xd prevents an unintended change of directory.
When xd is merely given an initial directory specification, like a single dot (.) or digit (a digit in
the set [0..9]) then xd returns the implied path. Specifying a parent before the root-directory (E.g.,
entering `xd 5’ when the current working directory is `/tmp’) results in writing the root directory (`/’)
to the standard output stream.
If xd is called without arguments then usage information is written to the standard error stream.
Xd may be further configured using options and a configuration file, discussed in the OPTIONS and
CONFIGURATION FILE sections below.
GENERALIZED DIRECTORY SEARCH
Starting with version 3.10.0 xd also supports generalized directory search command processing (GDS). When
GDS is requested separators are no longer required, and xd will find all possible alternatives resulting
from all possible sequential combinations of the initial search command. GDS is activated either by
specifying the -g command line flag or by entering generalized-search in xd’s configuration file.
Alternatively, when the latter is specified then the --traditional command line option will suppress GDS.
When using GDS each initial substring of the command to xd is considered as the initial characters of a
directory. E.g., if the command xd tmps is entered using GDS then directories matching the following
search patterns will be found;
o /t*/m*/p*/s*/
o /t*/m*/ps*/
o /t*/mp*/s*/
o /t*/mps*/
o /tm*/p*/s*/
o /tm*/ps*/
o /tmp*/s*/
o /tmps*/ Using the traditional processing mode only the first one of these alternative patterns is
considered.
Multiple command line arguments, the slash and the underscore can still be used with GDS in which case
they force a directory change in the considered patterns. E.g., with the command xd tm/ps the following
patterns will be considered:
o /t*/m*/p*/s*/
o /t*/m*/ps*/
o /tm*/p*/s*/
o /tm*/ps*/ In this set all of the previous patterns showing the ...mp... combination were dropped,
as a directory change is forced between the m and p characters.
RETURN VALUE
Xd returns 0 to the operating system unless an error occurs (e.g., when a non-existing configuration file
is specified), or xd’s version or usage info is shown or requested.
OPTIONS
If available, single letter options are listed between parentheses following their associated long-option
variants. Single letter options require arguments if their associated long options require arguments as
well.
o --add-root condition
If the search starts at the user’s home directory an additional search starting at the system’s
root directory may be performed as well, depending on the value specified for the add-root option.
Alternatives are never (no additional search is performed); if-empty (an additional search is
performed if the initial search did not yield any directory); or always (an additional search is
always performed). There is also a configuration file directive add-root (see below).
o --all -a
If the configuration file (see below) contains ignore directives then these directives are ignored
when computing the alternatives from which the user may select a directory to change to.
o --config-file=filename (-c)
The name of an xd configuration file. By default xd looks for the file .xdrc in the user’s home
directory. The existence of the default file is optional.
o --directories inclusion
Directories may be also be reached via symbolic links. The inclusion type all adds these symbolic
links to the list of alternatives. The inclusion type unique prevents symbolic links from being
added to the list of alternatives. There is also a configuration file directive directories (see
below).
o --homedir-char ch
By default an initial dot character (`.’) initiates a search from the user’s home directory. There
is a slight disadvantage to using the dot, as it is also be the initial character of `hidden’
directories. Assuming that you have a directory ~/.ssh then the command to xd to that directory
would be xd ..s, the first dot being the home directory indicator, after which .s is used to find
.ssh. The option --homedir-char can be used to specify another character. Homedir characters
cannot be digits or a slash (`/’) as these are used to specify, respectively, parent directories
and the computer’s root directory. Characters like ``, @ % ^’’ or maybe `H’ (assuming that it
doesn’t interfere with an existing directory beginning with H) could be used as
homedir-characters, other than the default dot character.
Caveat: command shells by default interpret characters like ``~ $ \ ’ " ` < > |’’ etc., which
therefore should probably not be specified as home directory specifiers.
There is also a configuration file directive homedir-char (see below).
o --generalized-search -g
When this option is specified xd uses GDS unless the directive traditional is specified in the
configuration file.
o --help (-h)
Basic usage information is written to the standard error stream.
o --history [filename]
A history of previously made choices is kept in the file filename. If --history is specified, but
the filename is left empty the history file $HOME/.xd.his is used. This file should only be
modified by xd itself. If you can’t resist editing it then use the following example showing the
format of the lines in the history file.
1292596154 1 /home/frank/svn/xd/
The first field is the time (in seconds since the epoch) the entry was written, the second field
is the number of times the entry has been selected and the third field is the associated path.
o --history-lifetime spec
The lifetime of the entries in the history file. The specification consists of a number followed
by D, W, M or Y, representing, resp. days, weeks, months, or years. A month is considered a period
of 30 days, a year a period of 365 days. If the specification is omitted a lifetime of 1M (one
month) is used. Entries older than history-lifetime are disregarded as history-items and are
removed from the history file.
o --history-maxsize nr
The maximum number of entries the history file may contain. By default there is no limit. When
history-maxsize is specified and more than the maximum number of history items are found in the
history file then the nr most popular choices are kept. Usually the cut-off point will be
somewhere within a popularity category. In that case the most recently selected alternatives
within that category are kept.
o --history-position [top|bottom]
When this option is specified then previously found alternatives are displayed either at the top
of the list or at the bottom of the list. If this option is omitted then the elements in the
history will be intermixed with new alternatives. The next option history-separate is only used
when this option is also specified. By merely specifying history-position the history items are
shown at the top of the list.
o --history-separate
When specified, a blank line is written between the items in the history and new alternatives (not
previously selected). This option is only interpreted when the previous option is also specified.
o --icase -i
This option is used to specify case-insensitive pattern matching. E.g., specifying xd /ub returns
the directory /usr/bin, but not a directory like /UnSpecified/Books, which is returned by xd /UB.
However, xd -i /ub (using any letter casing for the specification) returns both directories. The
option icase could of course be specified in the configuration file, which which case
case-insensitive matching is used by default. In the latter case specifying -i as a command line
option reverts the matching procedure to case-sensitive directory matching. In general, when an
even number of icase specifications is provided xd uses case-sensitive directory matching, while
an odd number of icase specifications results in case-insensitive directory matching.
o --start-at origin
Defines the default start location of directory searches. Origin home results in all default
searches to start at the user’s home directory. Origin root results in searches to begin at the
disk’s root (/) directory. There is also a configuration file directive start-at (see below).
o --traditional
When this option is specified xd will not use GDS but will use its traditional mode. It overrules
a generalized-search directive specified in the configuration file as well as the -g option.
o --verbose (-V)
More extensive information about the actions taken by the xd program is written to the standard
error stream.
o --version (-v)
Xd’s version number is written to the standard error stream.
CONFGURATION FILE
The default configuration file is .xdrc in the user’s home directory. It may be overruled by the
program’s --config-file option.
Empty lines are ignored. Information at and beyond #-characters is interpreted as comment and is ignored
as well.
All directives in xd configuration files follow the pattern
directive value
but for some directives value is optional.
A line may at most contain one directive, but white space (including comment at the end of the line) is
OK. The same directive may be specified multiple times, in which case the last directive will be used
(with the exception of the ignore directive, see below). All directives are interpreted case
sensitively. Non-empty lines not beginning with a recognized directive are silently ignored.
The following directives can be used in the configuration file. Default values are shown between
parentheses.
o add-root when (if-empty)
If the search starts at the user’s home directory an additional search starting at the system’s
root directory may be performed as well, depending on the value specified for the add-root
directive.
If when is specified as always then an additional search is always performed.
If it is specified as if-empty then an additional search is performed if the initial search
(starting at the user’s home directory) did not yield any directory.
If it is specified as never no additional search is performed.
This directive is overruled by the ---add-root command line option.
o directories which (all)
Directories may be also be reached via symbolic links. The specification all will add these
symbolic links to the list of alternatives. The specification unique will prevent the symbolic
links from being added to the list of alternatives.
This directive is overruled by the ---directories command line option.
o homedir-char ch
By default an initial dot character (`.’) initiates a search from the user’s home directory. There
is a slight disadvantage to using the dot, as it is also be the initial character of `hidden’
directories. Assuming that you have a directory ~/.ssh then the command to xd to that directory
would be xd ..s, the first dot being the home directory indicator, after which .s is used to find
.ssh. The specification homedir-char ch can be used to specify another home directory indicating
character ch, as in:
homedir-char ,
Homedir characters cannot be digits or a slash (`/’) as these are used to specify, respectively,
parent directories and the computer’s root directory. Characters like ``, @ % ^’’ or maybe `H’
(assuming that it doesn’t interfere with an existing directory beginning with H) could be used as
homedir-characters, other than the default dot character.
Caveat: command shells by default interpret characters like ``~ $ \ ’ " ` < > |’’ etc., which
therefore should probably not be specified as home directory specifiers.
This directive is overruled by the ---homedir-char command line option.
o generalized-search
When this directive is specified xd will use GDS by default.
o history [filename]
A history of previously made choices is kept in the file filename. If history is specified, but
the filename is left empty the history file $HOME/.xd.his is used. This file should only be
modified by xd itself. If you can’t resist editing it then use the following example showing the
format of the lines in the history file.
1292596154 1 /home/frank/svn/xd/
The first field is the time (in seconds since the epoch) the entry was written, the second field
is the number of times the entry has been selected and the third field is the associated path.
o history-lifetime spec
The lifetime of the entries in the history file. The specification consists of a number followed
by D, W, M or Y, representing, resp. days, weeks, months, or years. A month is considered a period
of 30 days, a year a period of 365 days. If the specification is omitted a lifetime of 1M (one
month) is used. Entries older than history-lifetime are disregarded as history-items and are
removed from the history file.
o history-maxsize nr
The maximum number of entries the history file may contain. By default there is no limit. When
history-maxsize is specified and more than the maximum number of history items are found in the
history file then the nr latest choices are kept. Each previously made selection counts as one.
If a new alternative is selected it always becomes an element in the history list.
o history-position [top|bottom]
When specified alternatives found in the history will be displayed either at the top of the list
or at the bottom of the list. If this option is omitted then the elements in the history will be
intermixed with new alternatives. The next directive history-separate is only used when this
directive is also specified. By merely specifying history-position the history items are shown at
the top of the list.
o history-separate
When specified, a blank line is written between the items in the history and new alternatives (not
previously selected). This directive is only interpreted when the previous directive is also
specified.
o --icase -i
This specification is used to request case-insensitive pattern matching. If this option is entered
in the configuration file then specifying xd /ub returns the directory /usr/bin as welll as a
directory like (assuming it exists) /UnSpecified/Books. When specified in the configuration file,
the command-line option -i reverts the matching procedure back to case-sensitive directory
matching. In general, when an even number of icase specifications is provided xd uses
case-sensitive directory matching, while an odd number of icase specifications results in
case-insensitive directory matching.
o ignore path
The configuration file may contain multiple ignore directives which are --different from the way
other directives are handled-- all interpreted. Each ignore directive is followed by a path
specification as shown in a list of alternatives produced by xd or an initial substring of such a
path terminating in a * character. When xd encounters a path matching any of the ignore directives
(with the * interpreted as `any further directory name’ specification) it will not display that
path in its list of alternatives.
This directive is overruled by the ---all command line option.
o start-at value (home)
Defines the default start location of directory searches. Values are home and root. When home is
specified all searches start at the user’s home directory. When root is specified searches start
at the disk’s root (/) directory. If the directory is omitted or if another value is specified
then the default is used, which is home.
This directive is overruled by the ---start-at command line option.
o traditional
This directive may be used to request the use of xd’s traditional mode. It overrules the -g
command line option and the generalized-search directive.
SHELL SCRIPTS
Assuming xd is installed in /usr/bin scripts can be defined around xd for various shell programs. This
allows the shell to change directories under control of xd.
To use xd with the bash(1)-shell, the following function can be used (which could be added to, e.g.,
.bash_login):
xd() # function to do `cd` using `xd`
{
cd "`/usr/bin/xd $*`"
}
To use xd with the tcsh(1)-shell, the following alias can be added to, e.g., the ~/.alias file:
alias xd ’cd `\xd \!*`’
If your system uses blanks in directory names, the above tcsh-alias cannot be used as the blanks are
interpreted as argument-separaters. In that case the following alias can be defined:
alias xd ’setenv XD "`\xd \!*`";cd "$XD"’
Having defined the xd alias or script xd ... commands results in the automatic (or optional) change of
the current working directory
EXAMPLES
xd ulb - all directories starting subsequently,
with u, l and b origin is default, or
specified in .xdrc as home or root
xd 0t - all directories starting with t below the cwd
xd 2t - all directories starting at the `grandparent’
(2 steps up) of the cwd
xd --start-at root t
- all directories at the root starting with t
xd .. - all directories starting with a dot in the cwd
xd . - the user’s home directory
xd 0 - the current working directory
xd 1 - the current directory’s parent directory
Assuming the following directories exist:
/usr/lib/bonobo
/usr/lib/bonobo-activation
/usr/local/bin
then the following two ignore specifications in xd’s configuration file will result in ignoring the
bonobo directory alternatives:
First specification:
ignore /usr/lib/bonobo
ignore /usr/lib/bonobo-activation
Second specification:
ignore /usr/lib/bonobo*
FILES
o $HOME/.xdrc: Default location of the configuration file
o https://fbb-git.gitlab.io/xd/: Home directory
BUGS
None reported
ABOUT xd
The program xd was initially (before 1994) written for the MS-DOS platform. In 1994 it was redesigned to
work under Unix (Linux, AIX) and it was converted to C++. The original C++ code is still available from
tag start (https://gitlab.com/fbb-git/xd/tags, find the start tag and download) and is funny to look at
as it is a remarkable illustration of C++ code written by C programmers who had just learned about C++.
Versions 2.x were used until 2008, and in late August 2008 I rewrote xd completely, reflecting my then
views about C++, eventually resulting in versions 3.x.y and beyond. The 3.x.y and later versions
extensively use the facilities offered by the bobcat(7) library.
ACKNOWLEDGEMENTS
GDS was added to xd following a suggestion by Bram Neijt (bram at neijt dot nl).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).