Syscall invokes the system call entry with the given arguments.
(Some functions, such as write and read(2), although not strictly
system calls, are valid entries.) It prints the return value and
the error string, if there was an error. An argument is either
an integer constant as in C (its value is passed), a string (its
is passed), or the literal buf (a pointer to a 1MB buffer is passed).
If –o is given, the contents of the 1MB buffer are printed as a
zero–terminated string after the system call is done. The –x and
–s options are similar, but –x formats the data as hexadecimal bytes,
while –s interprets the data as a stat(5) message and formats it
similar to the style of ls –lqm (see ls(1)), with extra
detail about the modify and access times.