RealView® Developer Kit Compiler and Libraries Guide B.1.2. Environment

B.1.2. Environment

The mapping of a command line from the ARM architecture-based environment into arguments to main() is implementation-specific. The generic ARM C library supports the following:

main()

The arguments given to main() are the words of the command line (not including input/output redirections), delimited by whitespace, except where the whitespace is contained in double quotes.

Note

A whitespace character is any character where the result of isspace() is true.
A double quote or backslash character \ inside double quotes must be preceded by a backslash character.
An input/output redirection is not recognized inside double quotes.

Interactive device

In an nonhosted implementation of the ARM C library, the term interactive device might be meaningless. The generic ARM C library supports a pair of devices, both called :tt, intended to handle keyboard input and VDU screen output. In the generic implementation:

no buffering is done on any stream connected to :tt unless input/output redirection has occurred
if input/output redirection other than to :tt has occurred, full file buffering is used (except that line buffering is used if both stdout and stderr were redirected to the same file).

Redirecting standard input, output, and error streams

Using the generic ARM C library, the standard input (stdin), output (stdout) and error streams (stderr) can be redirected at runtime. For example, if mycopy is a program, running on a host debugger, that copies the standard input to the standard output, the following line runs the program:


mycopy < infile > outfile 2> errfile

and redirects the files as follows:

stdin: The file is redirected to infile.
stdout: The file is redirected to outfile.
stderr: The file is redirected to errfile.

The permitted redirections are:

0< filename: This reads stdin from filename.
< filename: This reads stdin from filename.
1> filename: This writes stdout to filename.
> filename: This writes stdout from filename.
2> filename: This writes stderr from filename.
2>&1: This writes stderr to the same place as stdout.
>& file: This writes both stdout and stderr to filename.
>> filename: This appends stdout to filename.
>>& filename: This appends both stdout and stderr to filename.

To redirect stdin, stdout, and stderr on the target, you must define:


#pragma import(_main_redirection)

File redirection is done only if either:

the invoking operating system supports it
the program reads and writes characters and has not replaced the C library functions fputc() and fgetc().

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