an argument to the batch files (\fB.cmd\fR or \fB.bat\fR) or to the command
processor (\fBcmd.exe /c\fR), because this causes truncation of command-line
(also the argument chain) on the first newline character.
But it works properly with an executable (using CommandLineToArgv, etc).
.PP
\fBArgument quoting\fR
.RS
Each argument of the \fBexec\fR command is mapped to an argument of the called
program by an adaptive quoting by adding quote characters (\fB"\fR) around the
arguments.
The arguments of the \fBexec\fR command are mapped to the arguments of the called
program. Additional quote characters (\fB"\fR) are automatically  added around
arguments if expected. Special characters are escaped by inserting backslash
characters.
.PP
If invoking batch files or other specific programs, the Windows environment
does execute programs mentioned in the arguments or replace environment
variables, which may have side effects (vulnerabilities) or break any already
existing quoting (for example, if the environment variable contains a special
character like a \fB"\fR).
The MS-Windows environment does execute programs mentioned in the arguments and
called batch files (conspec) replace environment variables, which may have side
effects (vulnerabilities) or break any already existing quoting (for example,
if the environment variable contains a special character like a \fB"\fR).
Examples are:
.CS
% exec my-echo.cmd {test&whoami}
  test
  mylogin
% exec my-echo.cmd "ENV X:%X%"
  ENV X: CONTENT OF X
.CE
In consequence, the following formatting is automatically performed on any
The following formatting is automatically performed on any
argument item:
.IP \(bu 3
Avoid subprogram execution:
Any special character argument containing a special character (\fB&\fR, \fB|\fR,
\fB^\fR, \fB<\fR, \fB>\fR, \fB!\fR, \fB(\fR, \fB)\fR, \fB(\fR, \fB%\fR)
is automatically enclosed in quotes (\fB"\fR). Any data quote is escaped by
appropriate sequences.
insertion of backslash characters.
.IP \(bu 3
Avoid environment variable replacement:
Any appearence of environment variable reference (\fB%\fR) is individually quoted
by \fB"\fR.
.PP
TCL 8.6.10 refined this quoting by adding quoting for data quotes and individual
quoting of "\fB%\fR".