syscall Command

Purpose

Performs a specified subroutine call.

Syntax

syscall [ -n ] Name [ Argument1 ... ArgumentN ] [  Name Argument1 ... ArgumentN ] ] ...

Description

The syscall command executes a system call interface program, which performs the subroutine call specified by the Name parameter. If you specify the -n flag, the syscall command performs the call n times. Arguments specified by the Argument parameter are passed to the subroutine without error checking. The Argument parameter can be expressed in the following formats:

Item Description
0x nnn Hexadecimal constant nnn.
0 nnn Octal constant nnn.
nnn Decimal constant nnn.
+nnn Decimal constant nnn.
-nnn Decimal constant nnn.
"string The character string "string".
'string The character string "string".
\string The character string "string".
#string The length of the character string "string".
&&n The address of the nth argument to this subroutine. (n=0 is the subroutine name.)
&n The address of the nth byte in an internal 10KB buffer.
$n The result of the nth subroutine. (n=0 is the first subroutine.)
string Anything else is a literal character string.

The syscall command prints a message and exits for unknown subroutines and for subroutines that return a value of -1.

Note: The syscall command understands the sleep subroutine as a special case subroutine.

Flags

Item Description
-n Specifies the number of times the syscall command performs the specified subroutine.
; Separates multiple subroutines (up to a maximum of 20) issued by the same invocation of the syscall command.

Examples

To simulate the C program fragment:

output=open("x", 401, 0755);
write(output, "hello", strlen("hello"));

enter:

syscall open x 401 0755 \; write \$0 hello \#hello
Note: Special shell characters must be escaped.

Files

Item Description
/usr/bin/syscall Contains the syscall command.