User`s guide

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Appendix A: dbx Commands

syscall catch [{call | return}]

Prints a list of all system calls caught upon entry (call) or

return (return). If you provide neither the call nor return

keyword, dbx lists all system calls that are caught.

syscall ignore [{call | return}]

Prints a list of all system calls not caught upon entry (call)

or return (return). If you provide neither the call nor return

keyword, dbx lists all system calls that are ignored.

syscall catch {call | return} {system_call | all}

Sets a breakpoint to stop execution upon entering (call) or

returning from (return) the speciﬁed system call. Note that

you can set dbx to catch both the call and the return of a

system call.

If you use the keyword all rather than giving a speciﬁc

system call, dbx catches all system calls.

syscall ignore {call | return} {system_call | all}

Clears the breakpoint to stop execution upon entering (call)

or returning from (return) the speciﬁed system call.

If you use the keyword all rather than giving a speciﬁc

system call, dbx clears the breakpoints to stop execution

upon entering (call) or returning from (return) all system

calls.

tag procedure Searches the tag ﬁle for the given procedure.

trace variable Whenever the speciﬁed variable changes, dbx prints the old

and new values of that variable.

trace procedurePrints the values of the parameters passed to the speciﬁed

procedure whenever your program calls it. Upon return,

dbx prints the return value.

trace [expression|variable] at line

Whenever your program reaches the speciﬁed line, dbx

prints the value of the variable if its value has changed.

If the expression is of type pointer, look at the data pointed

to and watch until it changes. If the expression is not of type

pointer, look at the 32 bits at that address (assume the

expression evaluates to an address).