List of commands and features of FreeCOM:


ALIAS - Display or change an alias

Requirements: FEATURE_ALIASES

Synopsis

  1. ALIAS
  2. ALIAS name '=' [ «string» ]

The first format without any argument displays all defined aliases.

The second format assigns the specified string to the alias with the specified name. If the string is empty, the named alias is removed.

Once an aliase is defined, a command line of the form: name { argument }
is replaced by: <<string>> { argument }
This mechanism is called alias expansion, because the alias name expands to the specified «string». To prevent alias expansion the command must be prefixed by one asterisk, e.g.: *name arguments

Examples

Example: 1

ALIAS dir=dir /w
C> dir
displays short directory listing from now on.

Example: 2

ALIAS
displays all currently defined aliases, e.g.: 
DIR=dir /w
in this case.

Example: 3

ALIAS dir=
removes the previously defined alias dir, thus, DIR displays the long output as by default again.

FEATURE_ALIASES - Command aliases

See also: ALIAS

If defined on compilation of FreeCOM, command aliases are supported.

New aliases are defined using the command:
ALIAS name '=' «string»

Aliases are removed using the command:
ALIAS name '='

When FreeCOM is interpreting a command line, the command -- the very first word -- is matched against all defined aliases. This word is separated from its arguments by whitespaces and cannot contain any path delimiters, such as backslashes or colons.
If the command matches an alias, the name is substituted by the «string»associated to the aliases, e.g. by defining the alias ls by:
ALIAS ls=dir /w/o

let FreeCOM interprete the command line:
C> ls /a

exactly as if one had typed in:
C> dir /w/o /a

To prevent the alias expansion an asterisk is prefixed before the command, e.g.:
C> *ls /a

really tries to execute the command:
ls /a

which usually is an external command.

Aliases may be used to hide or re-place internal commands, e.g.:
ALIAS dir=xdir

effectively hides the internal command DIR and will always execute the -- usually -- external command XDIR.

Aliases may be nested, so if both alias definitions mentioned above are in place, the command:
C> ls /a

is really executed as:
xdir /w/o /a

where the ls command is substituted by the command dir /w/o, then dir is detected as alias, too, and hence replaced by xdir.
The same alias is never substituted twice, neither directly nor transitively, so:
ALIAS dir=dir /w

is allowed as well as:
ALIAS ls=dir /w/o
ALIAS dir=ls -l

command results in
ls ls -l /w/o
dir dir /w/o -l

As implied above, aliases are expanded when needed and not when they are defined.

Aliases are storred for each instance of FreeCOM individually and are inherited by secondary instances from the parent.

Options

Compile-time options:

BEEP - Issue a Beep

Requirements: CMD_BEEP

Synopsis

BEEP

Issues a beep.
At this time FreeCOM supports audible beeps only.

BREAK - Display or Set Extended Break Checking

Requirements: CMD_BREAK

Synopsis

BREAK [ ON | OFF ]

Displays or sets the Extended Break status.

By pressing ^Break or ^C (Control-Break or Control-C) an user may signal the currently running program to halt. Most programs will abort to the prompt, but some may decide to just cancel the current action, but remain active.

DOS checks for ^Break/^C (Control-Break or Crontrol-C) each time a program issues a console input/output request. When Extended Break checking is enabled (ON), DOS checks for ^Break each time a program issues a request.

CALL - Call a Nested Batchfile or Program

See also: LOADFIX, LOADHIGH
Optional requirements: FEATURE_KERNEL_SWAP_SHELL

Synopsis

  1. CALL [/Y] program [ «arguments» ]
  2. CALL [/Y] [ /S | /N ] program [ «arguments» ]

Calls a program or batch script.

If the program is a batch script, that means it has the extension .BAT, CALL nests the batch script within the already running one. Without CALL the invoked batch script would terminate all already running batch scripts.

If present, the arguments are passed unchanged to the invoked program.

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Note: In the future to swap FreeCOM out of memory during the execution of an external program will be the default behaviour.

CANCEL - Terminate all scripts

Synopsis

CANCEL [ n ]
Terminates all currently active batch scripts and, if present, assigns the specified number n to the errorlevel.

Note: This command is a hidden internal command.

CD - Change current directory of a drive

See also: CDD, CHDIR, DIR, DIRS, MD, PUSHD, RD
Requirements: CMD_CHDIR
Optional requirements: FEATURE_LAST_DIR

Synopsis

  1. CD
  2. CD [ drive ':' ] path
  3. CD '-'
CD is 100% compatible with the CHDIR command; there is no difference -- beside the spelling -- between them.

The first variant shows the current working directory as absolute path.

The second variant changes the current directory of the given drive. If no drive is specified on command line, the current directory of the currently selected drive (disk) is changed. This command does not change the currently selected drive in opposite to CDD!

The third variant changes back into the last visited directory and drive. The commands CD, CHDIR, CDD, and PUSHD save the current working directory before performing the specified directory change; the command CD '-' restores this saved directory. This command is available only, if the feature LAST_DIR has been enabled during the compilation of FreeCOM.

Options

There are no options for this command.

Examples

Example: 1

CD \freedos\help
Changes the current working directory of the currently selected drive to the path \FREEDOS\HELP.

Example: 2

CD c:\freedos\help
Changes the current directory of drive C:.

Example: 3

Assuming the current working directory is \FREEDOS\HELP and the currently selected drive is C:. CD
Displays C:\FREEDOS\HELP

Example: 3

The command sequence, provided the first two worked successfully:
CD \FREEDOS\HELP
CD ..
CD -
changes first into the directory \FREEDOS\HELP, then into its parent directory, which is \FREECOM. And finally CD - changes back to \FREEDOS\HELP, because this was the previous directory before previous CD-like command.

Because CD - saves the previous directory, too, any subsequent: CD -
will switch between these two directories; until another directory is changed to.

CDD - Changes the current working directory

See also: CD, DIR, MD, PUSHD, RD
Requirements: CMD_CDD

Synopsis

  1. CDD
  2. CDD [ drive ':' ] path
  3. CDD '-'
The behaviour of CDD is similiar to the CD command, but it always changes both the currently selected drive and the current directory, thus, it changes the current working directory.

For further details please see the CD command.

CHDIR - Change current directory of a drive

This command is 100% compatible to CD, please see there

CLS - Clear screen

See also: ECHO, TYPE
Requirements: CMD_CLS

Synopsis

CLS
Clears the screen and resets the character colours to white on black.

COPY - Copy one or more files to another location

See also: DEL, REN
Requirements: CMD_COPY

Synopsis

  1. COPY [{ option }] source [{ option }] target [{ option }]
Copies the source file into the target file. See also: \REF{wildcards}

Before parsing its command line COPY parses any option specified by the environment variable COPYCMD.

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Arguments

CTTY - Change TTY (console)

Requirements: CMD_CTTY

Synopsis

CTTY device
With this command the console device can be changed. A console device performs all basic input and output operations. This change is more complete than IO-redirections, because latter one might not catch all output, for instance the error messages. See example 3 below.
Because the console is a bidirectional virtual device, meaning it is to perform input and output, the specified device must not a unidirectional device, such as PRN.

To specify a second argument on the command line of FreeCOM has the same effect.

Attention: This command is to effect the whole system, not only FreeCOM itself; so the effect of CTTY does not only depend on the implementation status of FreeCOM, but on the DOS kernel, too.

Also, some programs access the screen or keyboard directly, rather than using the DOS functions; these programs are not effected by CTTY.

Examples

Example: 1

CTTY aux
Changes the console to the AUX: device, which is usually the first serial communication port COM1:. If this line is connected to a terminal or a terminal emulator, the system can be controlled from the terminal by now.

Example: 2

CTTY nul
any command sequence
CTTY con
The first command discards any output. If a program attempts any input operation, it gets none. Some programs may not handle such situation correctly.
So, any output, even error messages, are discarded during the command sequence.
The second command changes the console back to the screen/keyboard pair.
To display a string onto screen or read from keybord the usual I/O-redirections may be used, for instance:

DATE - Display or set current date

See also: TIME
Requirements: CMD_DATE

Synopsis

  1. DATE [ /D ]
  2. DATE [ /D ] date
The first variant displays the current system date, then enters a loop prompting the user for a new date. The loop terminates, if the user entered a valid new date or just pressed the ENTER key.

The second variant does not display the current date and tries to change the date to the specified date. On success the command terminates, otherwise enters the loop explained above.

The individual portions of a date may be separated by at least: dots ., forward slashes / or dashes -. Other nationally used characters may be supported, too.
DATE will support partial formats:


Symbolical names of monthes are not support (yet).

Options

All options must precced any argument.

/D prevents from prompting the user.

  1. In variant 1, the date is displayed only.
  2. In variant 2, the date is tried to be changed, but the loop is not entered on failure.

Examples

Example: 1

DATE /D
Just display the current system date.

Example: 3

DATE 2/1/00
Sets the current date to 1st February of 2000.

DEL - Delete files

See also: DIR
Requirements: CMD_DELETE

Synopsis

DEL [{ options | pattern }]
Deletes files, if pattern matches a directory, all files within this directory are deleted.

When all files are to be deleted, a warning prompt is issued.

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

DEL FILE1.EXT FILE2.EXT
Deletes the files FILE1.EXT and FILE2.EXT.

Example: 2

DEL /P *.bak
Deletes all files with extension BAK, but prompts the user for each single file before deleting it.

Example: 3

DEL.
Deletes all files within the current directory.

DIR - Displays the contents of the directory

See also: CHDIR, MKDIR, RMDIR
Requirements: CMD_DIR

Synopsis

DIR [{ options | pattern }]

DIR displays the contents of direcories and/or the attributes of files, whatever the pattern specifies. If no pattern is specified on command line, the current working directory is displayed. The actual information displayed depends on the specified options and is explained below.

A pattern may contain wildcards, which are expanded against both files and directories. To specify a directory is essentially equal to write: directory\*.*.

Unlike options patterns are performed in sequence, that means that if two patterns are specified, first all entries matching the first one, then all entries matching the second one are displayed; instead of to display the matching entries intermixed.

Before parsing its command line DIR parses any option specified by the environment variable DIRCMD.

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

DIR
Displays the contents of the current directory, but ignore System and Hidden files. The output may look like this: 
!!todo!!

Example: 2

DIR a* bb* *.txt
First displays all files, that begin with the letter A; then all files, that begin with two letters B, are displayed and at last all files with the extension TXT.

Example: 3

DIR /w a* b*
DIR a* /w b*
DIR a* b* /w
Because the position of options is not significant, all these examples behave the same way and display the matching files in wide or also called short form, which may look like this: 
!!todo!!

DIRS - Display the directory stack

See also: CD, CHDIR, POPD, PUSHD
Requirements: CMD_DIRS

Synopsis

DIRS
Displays all directories stacked with the PUSHD command.

ECHO - Displays a string onto screen

See also: TYPE
Requirements: CMD_ECHO

Synopsis

  1. ECHO [ ON | OFF ]
  2. ECHO «string»
  3. ECHO.
When executing a batch script each line is displayed to the console before executing it by default. The first variant of ECHO enables or disables this behaviour. To disable echoing the commands is equal to prefix each line of a batch script with the Ad-symbol @.
If ECHO is invoked with no argument at all, the current echo status is displayed.
When entered on an interactive command line the echo status controls whether or not the PROMPT string is displayed.

The second variant displays the specified «string».
Note: Because of variant 1 «string» may not expand to the single words ON or OFF without another character.

The third variant displays an empty line. No space must be placed between the dot and ECHO.

Examples

Example: 1

ECHO
Displays the current echo status, e.g. responding: 
ECHO is on

Example: 2

@ECHO OFF
Disables the echo status. Because the Ad-sign @ disables the echo status right for this line, this command disable echoing all the next lines of a batch script and is not echoed to the console itself. It is, therefore, best placed in the first line of a batch script.

Example: 3

ECHO Just a text
Displays Just a text

FEATURE_ENHANCED_INPUT - Enhanced command line editing

See also: FEATURE_FILENAME_COMPLETION, FEATURE_HISTORY

If enabled on compilation of FreeCOM, enhanced command line editing features are activated. Otherwise, FreeCOM uses the default buffered input DOS API function #0A.

If this feature is disabled, neither command line history nor filename completion is available.

Besides the other features various key bindings recognized, which are listed in the general FreeCOM documentation.

ERASE - Delete files

This command is 100% compatible to DEL, please see there

EXIT - Terminate shell

Synopsis

EXIT
Terminates the currently running shell, unless FreeCOM had been started with the /P option. In this case, EXIT works like CANCEL.

FEATURE_AUTO_REDIRECT_TO_CON - Autoswitch CON: to monitor

If defined on compilation of FreeCOM and if FreeCOM is to terminate although it is forbidden -- e.g. by passing the /P option when executing FreeCOM --, the console is changed to the keyboard/monitor pair automatically after some insuccessful prompts to reboot the system.

Options

Compile-time options:

FEATURE_BATCH - Batch script processing

Requirements: IMPLICIT

The batch script processing is always enabled.

Options

Compile-time options:

ENVIRONMENT_KEEP_FREE - keep free space in environment segment

If defined on compilation of FreeCOM, FreeCOM tries to keep the unused space in the environment segment equal to or greater than ENVIRONMENT_KEEP_FREE. The default value is 256.

FEATURE_BOOT_KEYS - check for F5/F8 keys on startup if /P is present

If defined on compilation of FreeCOM, FreeCOM waits three seconds on startup, if the /P switch is present. If during this time a key has been pressed, F5 will bypass AUTOEXEC.BAT execution and F8 will enable trace mode.
F5 is equal to to pass the /D switch to FreeCOM.
F8 is equal to to pass the /Y switch to FreeCOM.

FEATURE_INSTALLABLE_COMMANDS - Installable Commands interface (MUX-AE)

If defined on compilation of FreeCOM, calls to the Installable Commands API are made before executing any command. The API is situated at MUX-AE, the Multiplexer interrupt 0x2F function 0xAE.

The interface is documented elsewhere, for instance RBIL (Ralph Brown's interrupt list).

FEATURE_NLS - use DOS NLS

If defined on compilation of FreeCOM, FreeCOM uses the information retrievable by the currently active DOS NLS using the API functions #65.

These information influence:

FEATURE_CALL_LOGGING - Startup logging

If defined on compilation of FreeCOM, all startups of a FreeCOM instance is logged into a file.

The drive the logfile is created on can be changed at run-time with the external tool PTCHLDRV.

Options

Compile-time options:

FEATURE_FILENAME_COMPLETION - Filename completion

Requirements: FEATURE_ENHANCED_INPUT

If defined on compilation of FreeCOM and if the enhanced command line editing is activated as well, the tabulatur key binding becomes available.

When the tabulator key is pressed, the word the cursor is located on actually or is immediately preceeding is separated and tried to match against files, like a DIR command would do, e.g. when hitting tab at the command line:
bar\f_ some arguments

-- where the underscore _ is to mark the location of the cursor and is no actual character -- causes FreeCOM to try to locate any files or directories matching the filename pattern bar\f*.*.
If none is found, a beep is issued to indicate that error and the command line remains unchanged.
Otherwise as many characters are appended to the filename as are the same for all found matches, e.g.:

  1. if exactly one match was found, its name is appened.
  2. if, for example, the files or directories: FOO, FUU.TXT or FUU are present in the directory BAR, no character is appened, because there are no equal characters following the already present f character.
  3. if, for example, the files or directories: FOO, FOO.TXT or FOO1.TXT are present in the directory BAR, the two characters OO are appened, because all found matches share these two characters immediately following the already present characers. Hence, the command line is expanded to:
    bar\FOO_ some arguments

    Please note that the case of all characters will match the case of the retrieved filenames.
In addition, because in the cases 2 and 3 the file completion was not complete because more than one match was found, a beep is issued. In this situation to hit the tabulator key a second time, without an intervueing other key press, causes to display all available matches, but keeps the command line unchanged otherwise.
If exactly one filename match was found, hence the file completion was complete, and if the found match is a directory, a backslash is appended to. This allows to walk into deep levels of directories speededly.

If the cursor had been placed, for instance, under the backslash in above mentioned command line, the full string bar\f had been tried to be completed as well. This behaviour differs from other implementations.

Options

Compile-time options:

FEATURE_DIRSTACK - Directory stack

See also: DIRS, POPD, PUSHD

This feature is automatically enabled, if PUSHD is enabled.

The directory stack pushes and pops directories on demand via the commands PUSHD and POPD. DIRS displays all pushed directories.

Please see the documentation of the mentioned commands.

Options

Compile-time options:

FEATURE_HISTORY - Command line history

See also: HISTORY
Requirements: FEATURE_ENHANCED_INPUT

If enabled on compilation of FreeCOM and the enhanced command line editing is acivated as well, the command line history becomes available.

When commands are enterred manually on the command line prompt of FreeCOM, old command lines are storred in the history and can be retrieved later using the key bindings of F3, F1 and the cursor Up and Down keys.
Without the command line history at most one line is cached.

The command:
HISTORY

displays all cached command lines.

The command:
HISTORY number

resizes the amount of bytes reserved to cache command lines to number bytes. Doing so all cached command lines are deleted.

Each instance of FreeCOM maintains its own command line history, which is initially inherited from the particular parent instance, if any.

Options

Compile-time options:

FEATURE_LAST_DIR - Change back to last directory

See also: CD, CDD, CHDIR, POPD, PUSHD

If defined on compilation of FreeCOM, every change of the current directory using an internal command records the previous directory and enables the - shortcut for CD, CDD and CHDIR.

Example:

C> CD \
C> CD freedos\bin
C> CD -
C> CD -

The first CD command changes into the root direcotry, the second into the directory \FREEDOS\BIN, any subsequent CD - commands will change between the root directory and \FREEDOS\BIN.

FOR - Repeat a command

Requirements: CMD_FOR

Synopsis

FOR '%' letter IN '(' { word | pattern } ')' DO «any command»
Executes «any command» for several values assigned to the variable letter. The values are read strictly left to right from the words and patterns enclosed in parenthises; where patterns are words containing wildcards and are replaced by all matching filenames.

Any occurence of a percent sign % and the specified letter is replaced by the current value of the FOR loop. Note: The letter is case-sensitively matched!

Warning #1: Unlike most commands I/O-redirections are passed forth to the command instead of to apply them to FOR itself, e.g.:
FOR %a IN (*.*) DO ECHO %a >q
repeatedly executes the ECHO command with the redirection >q, hence, effectively overwriting the file each time.
Warning #2: Due the syntactical problem that the FOR variable is specified as '%' letter, which is also a legal start of an environment variable, the following kludge had been included to support FOR and its special variables:


Warning #3: Due a bug in MS COMMAND (BugID #1050) the right parenthesis must be followed by at least one whitespace, this allows the "feature" to embed such characters within the words and patterns, e.g.:
FOR %a in (a()a b()b) DO command
executes the command two times, first replacing %a by a()a, second by b()b.

Examples

Example: 1

FOR %z IN (*.*) DO copy %a a:
Performs a COPY xyz A: command for each file in the current directory. Its behaviour is equal to COPY *.* A:

Example: 2

FOR %z IN (a?b*.TXT) DO CALL batch arg %z
Executes the batch script batch.bat for each file matching the pattern A?B*.TXT located in the current directory. Within the script, the automatic variable %1 always expands to the constant argument arg, whereas %2 expands to the filename of the current loop.

Example: 3

FOR %a IN (1 2 3 4 5) DO ECHO %a
Is equal to the command sequence:
ECHO 1
ECHO 2
ECHO 3
ECHO 4
ECHO 5
Because these words do not contain no wildcards, they are not matched as filenames.

Example: 4

FOR %g IN (1 2 3*) DO ECHO %g
Performs the commands:
ECHO 1
ECHO 2
and the ECHO command for each file in the current directory, that has no extension and which name starts with the digit three.

GOTO - Goto label

Requirements: CMD_GOTO

Synopsis

GOTO [ ':' ] label
Normally all commands of a batch script are executed in the sequence in which they are appear with the script. GOTO controls the command flow by unconditionally jumping to the specified label; the commands following that label will be executed then. A label is written as a colon in the first column of a line and the name of the label immediately behind. If FreeCOM hits a label in the normal flow, it is ignored completely, even any redirection characters are ignored.

The label must be located in the same script file as the GOTO itself, if it appears more than once, the first occurance takes precedence.

Conditional jumps can be contructed with help of the IF command, see example 2.

Examples

Example: 1

GOTO ende
Jumps the to label :ende

Example: 2

IF "%1"=="" GOTO emptyCommandLine
Jumps to label :emptyCommandLine, if no argument had been passed to the batch script. For instance: 
@ECHO OFF
IF "%1"=="" GOTO error
REM do something sane here
GOTO ende

:error
ECHO You must pass an argument to me!

:ende

HISTORY - Display command line history

Requirements: FEATURE_HISTORY

Synopsis

  1. HISTORY
  2. HISTORY number

The first format without any argument displays all cached command lines.

The second format resizes the memory pre-allocated for the command line history cache to number bytes.

IF - Conditional execution of a command

Synopsis

  1. IF [ NOT ] EXIST file «command»
  2. IF [ NOT ] ERRORLEVEL number «command»
  3. IF [ NOT ] string '==' word «command»
  4. IF [ NOT ] quoted-string '==' quoted-string «command»
Conditionally executes the specified «command». If the keyword NOT is specified, the condition is negated, meaning, the «command» is executed, if the condition evaluates to false.

The first condition evaluates to true, if the specified file exists. Wildcards are supported. On local file systems one can test for character devices, too.

The second variant evaluates to true, if the errorlevel is currently assigned to a number greater or equal than the specified number. Errorlevels are assigned when external commands terminates or via CANCEL or QUIT.
Due to compatibly with other DOS shells FreeCOM does not check, if the specified errorlevel is a number, but silently accepts any string. This allows to use the so-called Benny levels, where you can specify HA, HB, ... , HZ or xa, xb, ... , xz instead of 1, 2, ... , 26. Some malformed batch script use this syntax to make mapping of errorlevels to drive letters more visible. See example 5.

The third and four ones are true, when the left string is case-sensitively equal to the string on the right side of the double equal sign. Either side may be quoted by double quotes, though, if the right side is not quoted, the first word is tested only.

Examples

Example: 1

IF NOT EXIST c:\command.com ECHO There is no COMMAND.COM in C:\

Executes the ECHO command, if a file C:\COMMAND.COM does not exist.

Example: 2

IF EXIST c:\fdos\nul GOTO have_fdos_directory

Branch the interpretation of the batch script to the label, if the file C:\FDOS\NUL exists. Because the filename NUL corresponds to the character device NUL:, which always exists, this test may be used to probe for the existance of the path C:\FDOS, because all character devices are virtually present in every directory of local filesystems.

Example: 3

IF %1==name ECHO First argument is "name"

ECHO is executed, if the first argument of the current batch script is "name" (without the quotes). %1 may expand to any string, even with embedded whitespaces, but without an embedded double equal sign. Also, metacharacters included within the argument are evaluated.

Example: 4

IF "%1"=="first name" ECHO First argument is "first name"

ECHO is executed, if the first argument of the current batch script is "first name" (without the quotes). %1 may expand to any string, even with embedded whitespaces or an embedded double equal sign or metacharacters.

Example: 5

«program»
SET drv=
FOR %%Z IN (A B C D E F G H I J K L M N O P Q R S T U V W X Y Z) DO IF ERRORLEVEL H%%Z SET drv=%%Z
IF ERRORLEVEL 27 SET drv=
IF "%drv%"=="" goto error_no_drive_letter

Assuming that «program» is setting the exit code to 1..26 for the drive letter, e.g. when searching for RAMdisks, this code snippet assigns the drive letter to the environment variable drv or unsets the variable on error.

Note: The following code is equal to the above one and fully compatible to all shells: «program»
SET drv=
IF ERRORLEVEL 1 SET drv=A
IF ERRORLEVEL 2 SET drv=B
IF ERRORLEVEL 3 SET drv=C

...
IF ERRORLEVEL 25 SET drv=Y
IF ERRORLEVEL 26 SET drv=Z
IF ERRORLEVEL 27 SET drv=
IF "%drv%"=="" goto error_no_drive_letter

FEATURE_LOAD_MESSAGES - Load messages permanently

If enabled on compilation of FreeCOM, the /MSG becomes available.

If this option is present, when an instance of FreeCOM is created, the FreeCOM messages are loaded into memory permanently. Otherwise, the messages are loaded on demand and are removed from memory when an external command is executed, in order to conserve memory.

This feature may help to run FreeCOM on disk- and floppyless boxes.

LOADFIX - Load an external program above the first 64KB memory

See also: CALL, LOADHIGH

Synopsis

LOADFIX program [{ argument }]
Loads and executes an exepacked program, that would abort execution with the error message "Packed file corrupt" otherwise.

Attention: This command is not available in the XMS-only variant of FreeCOM!

Example:

LOADFIX program.exe

LOADHIGH - Load an external program into high memory

See also: CALL, LOADFIX

Synopsis

LOADHIGH [{ option }] program [{ argument }]
Loads and executes an external program in high memory, also called UMB. This command is used to load TSRs, such mouse drivers, into the upper memory to conserve the conventional memory for programs.

Example:

LOADHIGH lmouse.com

MD - make directory

See also: CD, MKDIR, RD
Requirements: CMD_MKDIR

Synopsis

MD path
Creates a directory of the specified name path. Any parent directories must already exist.

Examples

Example: 1

MD C:\1

Creates the directory 1 in the root directory of drive C:.

Example: 2

MKDIR C:\1\2\3

Creates the directory 3 in the directory \1\2 of drive C:. If the directory C:\1\2 does not exist, yet, the command fails.

MEMORY - Display the internally used memory

Requirements: CMD_MEMORY

Synopsis

MEMORY

Displays the useage of internal memory of FreeCOM. Note: The internals of FreeCOM are currently under heavy construction, the actual output might vary heavily from this example.

Examples

MEMORY
may display this: 
Environment segment    : max  1200 bytes; free     8 bytes
Context segment        : max  2304 bytes; free  2252 bytes
        Aliases        : limit  1024 bytes, current     5 bytes,     0 items
        History        : limit   256 bytes, current    34 bytes,     2 items
        Directory stack: limit   256 bytes, current     5 bytes,     0 items
        Last dir cache : used      0 bytes,     0 items
        Swapinfo       : used      0 bytes,     0 items
Heap                   : free 482080 bytes

MKDIR - Make directory

This command is 100% compatible to MD, please see there

PATH - Display or set the search path

Requirements: CMD_PATH

Synopsis

  1. PATH
  2. PATH [ '=' ] { path : ';' }
  3. PATH;
Displays or assigns a new search path.

The first variant displays the currently active search path.

The second one assigns the specified paths to the search path. The leading equal sign, if present, is ignored.

The third variant empties the search path.

When FreeCOM searches for an external command or a batch script, which has no path specified, it is search for in all the directories specified in the search path. If the current directory . is not mentioned in the search path, it is searched through first.

Examples

Example: 1

PATH c:\fdos\bin;c:\tools;d:\others\bin;bin

If FreeCOM is to execute an external program, e.g. XCOPY, FreeCOM will search for the program in the following directories in the specified order, the first program file found is executed:
  1. the current directory
  2. C:\FDOS\BIN
  3. C:\TOOLS
  4. D:\OTHERS\BIN
  5. BIN

Note: Because the last directory specification is a relative one, rather than an absolute one, the program is searched for in the sub-directory BIN of the current directory.

PAUSE - Pauses batch file execution

Requirements: CMD_PAUSE

Synopsis

  1. PAUSE
  2. PAUSE «string»

Pauses the batch file execution until a key is pressed.

PAUSE prompts the user with the specified string or, if none is specifed, "Press any key to proceed"

Examples

Example: 1

PAUSE
Just pauses the execution.

Example: 2

PAUSE Execution paused, press any key to proceed ...
Pauses execution displaying this string.

Example: 3

PAUSE >nul
Pauses execution, but does not display any prompt.

POPD - Change back to the last pushed directory

See also: CD, CDD, DIRS, POPD
Requirements: CMD_CDD, CMD_POPD

Synopsis

  1. POPD
  2. POPD '*'

The first variant changes the current directory back to the one, in which the last PUSHD command was executed.

The second one clears all entries of the directory stack, but does not change the current directory.

PROMPT - Display or set the shell prompt

Requirements: CMD_PROMPT

Synopsis

PROMPT
PROMPT [ '=' ] prompt

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

PUSHD - Push the current working directory onto the directory stack

See also: CD, CDD, DIRS, POPD
Requirements: CMD_CDD, CMD_PUSHD

Synopsis

PUSHD directory

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

QUIT - Terminate the current script

Synopsis

QUIT [ n ]
Terminates the current active batch script and, if present, assigns the specified number n to the errorlevel.

Note: This command is a hidden internal command.

RD - Remove directory

See also: CD, MD, RMDIR
Requirements: CMD_RMDIR

Synopsis

RD path

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

REM - Marks comments or remarks in batchfiles

Requirements: CMD_REM

Synopsis

REM «string»

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

REN - Rename files

See also: RENAME
Requirements: CMD_RENAME

Synopsis

REN «source» «destination»
Renames the source file(s) into the target file(s). See also: \REF{wildcards}

The «destination» must not contain any path specification, the «source» file is renamed within the directory it is currently located in, see example 2 below. Any wildcards used within «destination» are replaced by the corresponding character of the source filename, see example 4 below.

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

REN file1.txt file2.txt
Renames file1.txt into file2.txt

Example: 2

REN path\file1.txt file2.txt
Renames path\file1.txt into path\file2.txt

Example: 3

REN path\file*.txt *.bak
Renames all files located within directory path with extension .txt and which filename is beginning with file, such as file.txt, filea.txt and file99xx.txt, into *.bak files.

Example: 4

REN *.DAT A*.*
Renames all files located within the current directory with extension .DAT into files by replacing the very first character of the filename by the letter A, all other characters, the file extension and path are remain unchanged.

Example: 5

REN *.TXT ??b*.bak
Renames all files located within the current directory with extension .TXT into files by replacing the third character of the filename by the letter B and the file extension to .BAK, all other characters and the file path are remain unchanged.

Warning: If the source file name consists of one character only, the second question mark in the destination pattern is ignored, hence, e.g. the file A.TXT is renamed into AB.BAK by this example, what is incompatible to MS COMMAND v6.22 (maybe others, too), which embedds a space as second character making the file inaccessable, but what is exactly the same behaviour of the same MS COMMAND's COPY command.

RENAME - Rename files

This command is 100% compatible to REN, please see there

RMDIR - Remove directory

This command is 100% compatible to RD, please see there

SET - Display or set environment variables

Requirements: CMD_SET

Synopsis

  1. SET [{ option }]
  2. SET [{ option }] variable '=' «string»

The first variant (without any argument) displays all the currently defined environment variables in the format (without any whitespaces before or after the equal sign): name '=' «value»

The second variant assigns a new value «string» to the specified variable. If the variable already exists, the old value is overwritten without notice; otherwise it is newly created.

Options

Unless stated otherwise all options of this command do follow the standard rules for options. All options must preceed the assigment, if present.

SHIFT - Shift the arguments of a batch script

Requirements: CMD_SHIFT

Synopsis

  1. SHIFT
  2. SHIFT DOWN

Shifts the arguments of a batch script one position up (first variant) or down (second variant).

Within a batch script the automatic variables %0 through %9 are replaced by the script name and the first nine arguments. This can be imagined as a window to ten arguments of the script. SHIFT will allow to move this window of ten arguments towards its end (up) or its start (down).

After SHIFT has been executed, the former %0 is hidden and inaccessable, %1 became %0, %2 became %1 a.s.o, %9 became %8 and the formerly hidden tenth argument became %9.
SHIFT DOWN reverses one SHIFT command.

SHIFT can be called as many times as wanted, SHIFT DOWN won't allow to underflow the very first argument.

Examples

Example: 1

If the batch script B.BAT:
@ECHO OFF
ECHO 0: %0
ECHO 1: %1
ECHO 2: %2
had been executed using:
B.BAT 1 2 3 4
it displays: 
B.BAT
1
2

If a SHIFT command had been inserted as second line, the same call displays: 
1
2
3

TIME - Display or set current time

See also: DATE
Requirements: CMD_TIME

Synopsis

  1. TIME [ /T ]
  2. TIME [ /T ] time
Variant 1 displays the current time, then enters a loop prompting the user to enter a new time. The loops terminates when a valid time had entered or the user just pressed the ENTER key.

Variant 2 does not display the current time, but tries to change the current time to the specified time, on failure the loop as explained above is entered.

The individual portions of a time may be sperated by at least: dots ., colons : and forward slashes /. Other nationally used characters may be supported, too. If a certain number of portions are specified:

  1. error,
  2. hour:minute; seconds and hundreds default to zero,
  3. hour:minute:seconds; hundreds defaults to zero,
  4. hour:minute:seconds.hundreds;
  5. more than 4 portions result in an error.
Separated by no, one or more whitespaces the am/pm modifiers may follow optionally. If present they alter the given time as follows:

Options

All options must preceed any arguments.

/T: prevents from prompting the user.

  1. In variant 1, the time is displayed only.
  2. In variant 2, the time is tried to be changed, but the loop is not entered on failure.

Examples

Example: 1

TIME /T
Just displays the current time.

Example: 2

TIME 18:2
Sets the current system time to 6:02 PM.

TRUENAME - Display the true name of a file

Requirements: CMD_TRUENAME

Synopsis

TRUENAME path

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

TYPE - Display the contents of files

See also: DIR, ECHO
Requirements: CMD_TYPE

Synopsis

TYPE { pattern }

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

VER - Display the version information about FreeCOM and DOS

Requirements: CMD_VER

Synopsis

VER [{ option }]

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

VERIFY - Display or set verify level

Requirements: CMD_VERIFY

Synopsis

VERIFY [ ON | OFF ]

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

VOL - Display the volume label of a drive

See also: DIR

Synopsis

VOL [ drive ]

Options

Unless stated otherwise all options of this command do follow the standard rules for options.

Examples

Example: 1

WHICH - Search and display the executable file of specified commands

Requirements: CMD_WHICH

Synopsis

WHICH [{ command }]

Searches for the specified command(s) the same way as if it would be specified on command line as command itself. If an executable file is found, its path is displayed in this format:
command «tab» path

The «tab» stands for the tabulator character (ASCII 9).
If the command is not found only the command part, but neither a path nor the «tab» is displayed.

Internal commands, installable commands and aliases are not found.

Examples

Example: 1

WHICH which
Returns a file or nothing, because WHICH is an internal command.

Example: 2

WHICH command
Could display for instance: 
command	C:\COMMAND.COM

Please note that command is the string "command" and no placeholder.

Appendix

Current Directory

The current directory is the default directory of a drive.

DOS stores a default directory for each drive. When a path is specified with a drive specification only, such as D:, it is completed with this default directory of that drive to construct the absolute path to be used.

Current Working Direcory

In opposite to the current directory the current working directory is the absolute path constructed out of the currently selected drive and current directory of that drive.

Path Specification

In DOS an absolute path is constructed out of several components:
  1. drive,
  2. directory,
  3. filename, and
  4. file extension.
like this: D:\DIR1\DIR2\FILENAME.EXT.

The drive is a single letter from A through Z followed by a colon :.

The remaining part of a path consists of similiar components delimited by a single backslash \. The last component is also called filename. Each of these components may be formed of a name, up to eight characters long, and an extension, up to three characters long. Both parts are delimited by a single dot .. Although the extension may be absent, the filename must have at least one character.
Note: The term filename is not limited to files in the usual sense, but may apply to any name visible in a directory, such as subdirectories and volume labels, as well.

To ease the way to enter a path the user may specify a relative path, rather than an absolute one. In such path one or more components may be missing:

Examples, assume the current directories of
Drive Current Directory
C: \FREEDOS\HELP
D: \TEMP\TEXT
The currently selected drive is C:.

  1. C:\
    The root directory of drive C:.
  2. .
    The current working directory, ergo: C:\FREEDOS\HELP.
  3. ..
    The parent directory, ergo: C:\FREEDOS.
  4. D:
    The current directory of drive D:, ergo: D:\TEMP.
  5. D:.
    The current directory of drive D:, ergo: D:\TEMP.
  6. D:..
    The parent directory of drive D:, ergo: D:\.
  7. ..\BIN
    Because there is neither a drive nor a leading backslash, both the currently selected drive and the current directory of that drive is inserted before the given path, ergo: C:\FREEDOS\HELP\..\BIN.
    The embedded component .. has the same meaning as when specified alone: parent directory, though, here in the context of the directory C:\FREEDOS\HELP\. That means that the final absolute path is: C:\FREEDOS\BIN.

Path specifications that do not conform to above mentioned format lead to various different behaviour of the various programs, because there is no standard to scan, parse and interprete such patterns. Problems include:

Note: The special directories . and .. are no phantom directories or virtual entries, but standard entries of every directory except the root directories. These entries help crash recovery tools, such as CHKDSK or SCANDISK, to find errors within the directory structure and restore it to a valid file tree. Therefore a common assumption that a tripple dot ... directory means parent-of-parent is incorrect, though, might be supported by certain programs.

Standard Rules for Options

Options are prefixed by one forward slash "/", the following character identifies the option and is called option character, for instance: /A

Some commands do accept long option names, where a complete word identifies the option rather than a single character, e.g. /MSG.

Some option may be used in conjunction with an argument. The argument is appended to the option with one colon ":" or one equal sign "=", for instance: /A:hr or /P=fdexec.bat.

Multiple options without argument maybe merged together as a single option with or without embedded slashes, e.g. /WS or /W/S, instead of /W /S.
However, because some commands do accept long option names, the way with embedded slashes is more secure and is recommended therefore.
An option with argument may be the last one of such merged options.

Options without arguments enable or disable certain features. Therefore, those options are sometimes called boolean options or flags.
Boolean options may be optionally prefixed by a plus "+" or minus "-" sign. So, the boolean option O can be written in three ways:

  1. /+O: The option is enabled.
  2. /-O: The option is disabled.
  3. /O: (neither plus nor minus sign) The option is toggled or flipped; this means if the option is enabled currently, it is disabled; but if it is disabled currently, it is enabled.

Without user invention a boolean option is disabled by default, so both /+O and /O behave the same most of the time. However, some commands allow the user to change the default settings of certain options, e.g. COPY and DIR.

I/O Redirection

In DOS the standard input and output can be redirected to a file or another device; however, although it is common to use these I/O streams today, some programmers cowardly ignore them for reasons of speed or program size.

If the input stream is redirected to a file or device, instead of polling the keyboard and request the user to interactively enter characters via the keyboard, those characters are read from the file or device. Usually these programs terminate when the file has been read wholely.

If the output stream is redirected to a file or device, instead of issuing the information onto screen, it is dumped into the file or device. Per convention each program has two output streams: one (called standard output) to issue normal information and one (called standard error output) for error messages the user should not miss.

Redirections are specified on command line and effect exactly that command invoked herein, regardless if the command is an external or internal one, an alias or batch script. The utter exception is the FOR command, which requires that the redirection is to apply to the command specified behind the DO keyword rather than FOR itself.
If more than one redirection is specified on the command line and they effect the same stream (input, output, or error), the rightmost one superceed any previous one.

Redirections are syntactically specified like this:
operator target
operator ::= '<' | '>' [ '>' ] [ '&' [ '>' ] ]
target ::= file | device

Although it is not relevant where the redirections are placed on the command line, it is common praxis to place them at the end of it.

The operators have the following meaning:
Operator Redirection
< Input stream
> Output stream; target file is overwritten
>> Output stream; output is appended to target, if it already exists
>& Output and error stream; target file is overwritten
>>& Output and error stream; output is appended to target, if it already exists
>&> Error stream; target file is overwritten
>>&> Error stream; output is appended to target, if it already exists

Examples

Example: 1

cmd <in1 <in2

Input stream is redirected to file IN2, because it is the rightmost one.

Example: 2

cmd <in >&out

Input stream is redirected to file IN, output and error streams are joined together and redireced into file OUT. If the file OUT already exists, the old contents is discarded and replaced by the new one; otherwise, the OUT is created anew.

Example: 3

cmd <in >>&out

As example 2, but instead of replacing the contents of OUT, if the file already exists, the new information is appended to the end of the file.

Example: 4

FOR %a IN (*.*) DO ECHO %a >out

As mentioned earlier, FOR is an exception and passes forth the redirections to each invocation of the command specified right of the DO keyword. So this examples overwrites the output file each time the ECHO command is performed, thus, instead of creating a file list, only the last found file is recorded into OUT.

Example: 5

IF EXIST out DEL out
FOR %a IN (*.*) DO ECHO %a >>out

This sequence eliminate the problem, the IF command is required to actually replace the file rather than appending the file list to the probably existent file.

Pipes

Another form of redirection is piping. Hereby, the output stream of one command is connected to the input stream of another command. Pipes can combine any number of commands this way. Because DOS is no multitasking system, pipes are simulated by spawning the first command with an output redirection capturing the issued information into a temporary file and then the second command with an input redirection from that very same temporary file, on completation of the second command the temporary file is deleted.

Examples

Example: 1

cmd1 | cmd2 | cmd3

Which is similiar to this sequence:
cmd1 >%TEMP%\t1
cmd2 <%TEMP%\t1 >%TEMP%\t2
DEL %TEMP%\t1
cmd3 <%TEMP%\t2
DEL %TEMP%\t2

Example: 2

The first and last command can have an input or output redirection respectively, like so:
cmd1 | cmd2 | cmd3 <in >out

Which is similiar to this sequence:
cmd1 >%TEMP%\t1 <in
cmd2 <%TEMP%\t1 >%TEMP%\t2
DEL %TEMP%\t1
cmd3 <%TEMP%\t2 >out
DEL %TEMP%\t2

Example: 3

The error stream can be piped as well:
cmd1 |& cmd2 | cmd3

Which is similiar to this sequence:
cmd1 >&%TEMP%\t1
cmd2 <%TEMP%\t1 >%TEMP%\t2
DEL %TEMP%\t1
cmd3 <%TEMP%\t2
DEL %TEMP%\t2

Here only the error messages of cmd1 are passed into cmd2; the error messages of both cmd2 and cmd3 are issued to the screen.

Nested redirections

Batch scripts or when external programs invoke other programs or another shell, redirections may be nested, e.g.:

Consider the batch file BATCH.BAT: 

@ECHO OFF
ECHO 1
ECHO 2 >out_2
ECHO 3
which is invoked via:
BATCH >out_1

When the script BATCH gets executed, the actual output stream is redirected to the file OUT_1. Therefore the output of the first ECHO command is redirected into this file.
Because the second ECHO command has its own output redirection, its output is redirected into the file OUT_2. On completion of ECHO the redirection is closed and the former one is restored.
What causes that the output of the third ECHO command is redirected into OUT_1 again.

Hidden Internal Commands

There are some special internal commands, that are not directly visible nor accessable. They are hidden because of two main purposes:
  1. Many of them are of internal nature and should not used by the user.
  2. They are extensions to the normal batch language and may, therefore, clash with a particular installation. To prevent this clash those commands are hidden by default and can be made directly accessable via the ICMD command.

Hidden internal commands can be access by prefixing the command with ::=. This token usually specifies a label within the batch language, given the nature of the labels, they may be comments as well. Due to the latter variant, most non-FreeCOM shells won't see the ::=, hence, ignore those commands.

For example: C> ::=CANCEL 30

cancels (terminates) all currently active batch files and assigns 30 to the current errorlevel.