ALIAS command
The ALIAS command defines or lists aliases commands. This command can be used to provide a logic close to macros provided by the Doskey command.
Synopsis
ALIAS [/f] [/l] [name[=command-block]]
Defines an alias that is internal to Picobat, or lists aliases
-
name : Name of the alias to be created.
-
command : The commands to be executed whenever name command is invoked. During the execution of the alias, $* is replaced by all the paremeters of the alias. The nine first parameters can also be accessed individually using $1 through $9 symbols. Note that these symbols are expanded before any delayed expansion is done on the command line.
-
/f : Creates an alias even if name corresponds to an already defined alias or internal command.
-
/l : Lists all current aliases or aliases matching name.
ALIAS allows redefining an internal command. This functionnality is interesting if you have to hook some internal command.
ALIAS does not check that the aliases it creates are not self-calling (eg. no circular declariation). If ALIAS is used to create such aliases, these aliases will lead to infinite loop when used.
By default, There is only one alias defined by pBat. It links HELP to HLP.
Making macros
The ALIAS command can be used to make very simple or complex macros. to define a command, you can use for example:
ALIAS my_command=echo some stuff
This will print “some stuff” every time my_command is invoked.
As explained above, parameters can be retrieved individually using the $1 to $9 symbols, and all of them can be using $*. As such it is possible to make some elaborate macros in order to perform specific action. For example the following macro changes the %PROMPT% variable before and after calling cmd.exe to fix bugs caused by Picobat incompatible prompt options:
alias cmd=(set prompt=$P$G^
cmd.exe $*^
set prompt=%PROMPT%)
The block is mandatory in order to have the lines executed as separated lines. The new lines must be escaped using ^ escape character or a syntax error will be yielded. On every call to cmd, the prompt variable is modified, then cmd.exe is run and finally the prompt variable is reset.
Both IF and FOR commands can be used in aliases so it is possible to run loops inside aliases, for example, the following macro can be used to compute the length of a string:
alias strlen=set $2=0 ^& for %%P in (4096 2048 1024 512 256 128 64 32 16 8 4 2 1) do (^
if "!$1:~%%P,1!" NEQ "" (^
set /a "$2+=%%P" ^
set "$1=^!$1:~%%P^!" ^
) ^
)
This macro uses $1 and $2 as parameter. The first parameter is a variable containing a string and the second is a counter to retrieve the length of the string. It can be used like so:
set string=my string example
strlen string counter
echo string "%string%" is %counter% characters long
Compatibility
Does not exist in cmd.exe. This is the closest equivalent of Doskey.exe though alias also works in batch scripts.