Instructs the file system to add or display cache buffers for a drive.
ADDBUFFERS adds <n> buffers to the list of buffers available for <drive>. Although adding buffers speeds disk access, each additional buffer reduces free memory by approximately 512 bytes. The default buffer allocation is 5 for sloppy drives and 30 for hard disk partitions.
The amount of extra available memory dictates the number of buffers you can add. There is no fixed upper limit; however, adding too many buffers reduces overall system performance by taking RAM away from other system functions. Specifying a negative number subtracts that many buffers from the current allocation. The minimum number of buffers is one; however, using only one is not recommended.
Twenty buffers are recommended for a floppy drive in a 512 KB system. Use the default value recommended by the HDToolBox program for hard disks. (Display this value by selecting the Advanced Options gadget on the Partitioning screen.)
If only the <drive> argument is specified, ADDBUFFERS displays the number of buffers currently allocated for that drive.
1> ADDBUFFERS DF0:
DF0: has 5 buffers
A further example of ADDBUFFERS appears in Chapter 8.
Sets or displays command aliases.
ALIAS creates aliases, or alternative names, for AmigaDOS commands. ALIAS can be used to abbreviate frequently used commands or replace standard command names with different names.
When AmigaDOS encounters <name>, it replaces it with the defined <string>, integrate the result with the rest of the command line, and attempts to interpret and execute the resulting line as an AmigaDOS command <Name> is the alias for the command and <string> is the command to be substituted for the alias.
An alias must be entered at the beginning of the command line. You can enter arguments after the alias, but you cannot create an alias to represent a series of command arguments. For example, in the following command line:
1> NEWSHELL WINDOW=CON:0/250/640/150/2SHELL/CLOSE
the WINDOW argument cannot be replaced with an alias.
You can substitute a file name or other instruction within an alias by placing square brackets ([ ]) with nothing between them in the <string>. Any argument entered after the alias is inserted at the brackets.
ALIAS <name> displays the <string> for that alias. Entering ALIAS alone lists all current aliases.
Aliases are local to the Shell in which they are defined. If you create another Shell with the NEWSHELL command, it shares the same aliases as its parent Shell. However, if you create another Shell with the Execute Command menu item, it des not recognize aliases created in your original Shell. A global lais that is recognized by all Shells can be crated by inserting the alias in the Shell-startup file.
To remove an ALIAS, use the UNALIAS command.
Entering d1 displays a directory of the contents of the disk in DF1:; as if you entered DIR DF1:.
creates an alias called HEX that displays the contents of a specified file in hexadecimal format. The empty brackets indicate where the file name is inserted in this example. Entering:
displays the contents of Myfile in hexadecimal format.
See also: UNALIAS. Further examples of using ALIAS appear in Chapter 8.
Gets yes or no user input during script file execution.
ASK is used in scripts to write the string specified by <prompt> to the current window and then wait for keyboard input. Valid keyboard responses are Y (yes), N (no), and Return (no). Selecting Y sets the condition flag to 5 (WARN). Selecting N or pressing Return sets the condition flag to 0. Check the response using an IF statement.
If the <prompt> contains spaces, it must be enclosed in quotation marks.
Assume a script contained the following commands:
ASK Continue?
IF WARN
ECHO Yes
ELSE
ECHO No
ENDIF
At the ASK command, Continue? Is displayed on the screen. If Y is pressed, Yes is displayed on the screen. If N or a Return alone is pressed, No is displayed.
See also: IF, ELSE, ENDIF, REQUESTCHOICE, WARN
Controls assignment of logical device names to files or directories.
ASSIGN allows references to files or directories with short, convenient logical device names, rather than their usual names or complete paths. The ASSIGN command can create assignments, remove assignments, or list some or all current assignments.
If the <name> and {<target>} arguments are given, ASSIGN assigns the given logical name to the specified target. Each time the assigned logical device name is referred to, AmigaDOS accesses the specified target. If the <name> given is already assigned to a file or directory, the new target replaces the previous one. A colon must be included after the <name> argument.
If only the <name> argument is given, any existing ASSIGN of a file or directory to that logical device name is cancelled.
You can assign several logical device names to the same target by using multiple ASSIGN commands.
You can assign one logical device name to several targets by specifying each file or directory after the <name> argument or by using several ASSIGN commands with the ADD option. Specifying the ADD option does not replace any existing target assigned to <name>. This target is added to the ASSIGN list and the system searches for all the targets when <name> is encountered. If the first target is not available, ASSIGN uses the next target added.
The REMOVE option deletes a target name from the ASSIGN list.
If no arguments are given with ASSIGN or if the LIST keyword is used, a list of all current assignments is displayed. If the VOLS, DIRS, or DEVICES switch is specified, ASSIGN limits the display to volumes, directories, or devices.
When the EXISTS keyword is entered with a logical device name, AmigaDOS searches the ASSIGN list for that name and displays the volume and directory assigned to that device. If the device name is not found, the condition flag is set to 5 (WARN).
When the {<target>} argument is given, AmigaDOS immediately looks for that file or directory. If the ASSIGN commands are part of the User-startup, the targets must be present on a mounted disk during the boot procedure. If an assigned target cannot be found, a requester asks for the volume containing it. However, using the DEFER and PATH options make the system wait until the target is needed before searching for it.
The DEFER option creates a late-binding ASSIGN. This ASSIGN takes effect when the assigned object is first referenced, rather than when the assignment is made. When the DEFER option is used, the disk containing the assigned target is not needed until the object is called. The assignment then remains valid until explicitly changed.
If you ASSIGN FONTS: to DF0:Fonts with the DEFER option, the system associates FONTS: with the disk that is in DF0: when FONTS: is referred to. For example, if you have a Workbench disk in DF0: at the time the FONTS: directory is needed, the system associates FONTS: with that particular Workbench disk. If you later remove that Workbench disk and insert another disk containing a Fonts directory, the system specifically requests the original Workbench disk the next time FONTS: is needed.
The PATH option creates a non-binding ASSIGN. A non-binding ASSIGN acts like a DEFERed ASSIGN, except that is re-evaluated each time the assigned name is referenced. For example, if you assign FONTS: to DF0:Fonts with the PATH option, any disk in DF0: is searched when FONTS: is referenced. As long as the disk contains a Fonts directory, it satisfies the ASSIGN. You cannot assign multiple directories with the PATH option.
Floppy disk only system users can find that using the PATH option eliminates the need to reinsert the original Workbench disk used to boot the system. As long as the drive you assigned with the PATH option contains a disk with the assigned directory name, the system uses that disk.
The DISMOUNT option disconnects a volume or device from the list of mounted devices. You must provide the device name in the argument. DISMOUNT removes the name form the list, but does not free resources. You cannot cancel a DISMOUNT without rebooting. DISMOUNT is meant for use by software developers only and can cause a software failure if not used carefully.
1> ASSIGN FONTS: MyFonts:Fontdir
assigns the FONTS: directory to Fontdir on MyFonts:
1> ASSIGN LIST
Volumes:
Ram Disk [Mounted]
Workbench [Mounted]
MyFonts [Mounted]
Directories:
LOCALE Workbench:Locale
KEYMAPS Workbench:Devs/Keymaps
PRINTERS Workbench:Devs/Printers
REXX Workbench:S
CLIPS Ram Disk:Clipboards
ENV Ram Disk:Env
T Ram Disk:T
ENVARC Workbench:Prefs/Env-Archive
SYS Workbench:
C Workbench:C
S Workbench:S
L Workbench:L
FONTS MyFonts:Fontdir
DEVS Workbench:Devs
LIBS Workbench:Libs
+ Workbench:Classes
Devices:
PIPE AUX RAM CON
RAW PAR SER PRT DF0
Shows a typical list of all current assignments. The plus sign indicates any additional directories with the same assignment.
1> ASSIGN FONTS: EXISTS
FONTS: MyFonts:FontDir
is an inquiry into the assignment of FONTS:. AmigaDOS responds by showing that FONTS: is assigned to the FontDir directory of the MyFonts volume. The return code is set to 0 if it exists or to 5 if it does not.
1> ASSIGN LIBS: SYS:Libs BigAssem:Libs ADD
is a multiple-directory assignment that creates a search path containing two Libs directories. Specifying ADD keeps the standard SYS:Classes assignment from being removed. These directories are searched in sequence each time LIBS: is invoked.
removes the DEVS: assignment from the system.
1> ASSIGN WorkDisk: DF0: DEFER
1> ASSIGN WorkDisk: EXISTS
WorkDisk <DF0:>
sets up a late-binding assignment of the logical device WorkDisk:. Until the first time you refer to the name WorkDisk:, you do not need to insert it in DF0: ASSIGN shows DF0: enclosed in angle brackets to indicate that it is DEFERred. After the first reference to WorkDisk:, the volume name of the disk that was in DF0: replaces <DF0:>.
1> ASSIGN C: DF0:C PATH
1> ASSIGN C: EXISTS
C [Df0: C]
references the C directory fo the disk that is in DF0: when a command is searched for. ASSIGN shows DF0:C in square brackets to indicate that it is a non-binding ASSIGN.
adds Zcad:Libs to the list of directories assigned as LIBS:.
1> ASSIGN LIBS: Zcad:Libs REMOVE
removes Zcad:Libs from the list of directories assigned as LIBS:.
For more examples using ASSIGN, see Chapter 8.
