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stapex(3stap) — Linux manual page

STAPEX(3stap)STAPEX(3stap)

NAME        top

       stapex - systemtap examples

LANGUAGE BASICS        top

       These examples give a feel for basic systemtap syntax and control       structures.              global odds, evens              probe begin {                # "no" and "ne" are local integers                for (i=0; i<10; i++) {                  if (i % 2) odds [no++] = i                  else evens [ne++] = i                }                delete odds[2]                delete evens[3]                exit ()              }              probe end {                foreach (x+ in odds) {                  printf ("odds[%d] = %d\n", x, odds[x])                }                foreach (x in evens-) {                  printf ("evens[%d] = %d\n", x, evens[x])                }              }       This prints:              odds[1] = 1              odds[3] = 5              odds[4] = 7              odds[5] = 9              evens[5] = 8              evens[4] = 6              evens[2] = 2              evens[1] = 0       Note that all variables types are inferred, and that all locals       and globals are automatically initialized.       This script prints the primes between 0 and 49.              function isprime (x) {                if (x < 2) return 0                for (i=2; i<x; i++) {                  if (x % i == 0) return 0                  if (i * i > x) break                }                return 1              }              probe begin {                for (i=0; i<50; i++)                  if (isprime (i)) printf("%d\n", i)                exit()              }       This script demonstrates recursive functions.              function fibonacci(i) {                if (i < 1) error ("bad number")                if (i == 1) return 1                if (i == 2) return 2                return fibonacci (i-1) + fibonacci (i-2)              }              probe begin {                printf ("11th fibonacci number: %d\n", fibonacci (11))                exit ()              }       Any larger number may exceed the MAXACTION or MAXNESTING limits,       and result in an error.

PROBING        top

       To trace entry and exit from a function, use a pair of probes:              probe kernel.function("sys_mkdir") { println ("enter") }              probe kernel.function("sys_mkdir").return { println ("exit") }       To list the probeable functions in the kernel, use the listings       mode.              % stap -l 'kernel.function("*")'       To list the probeable functions and local variables in the kernel,       use another listings mode.              % stap -L 'kernel.function("*")'

MORE EXAMPLES        top

       The directory to find more examples can be found in the stappaths       (7) manual page, and online athttp://sourceware.org/systemtap/examples/

SEE ALSO        top

stap(1)stapprobes(3stap)stappaths(7)

COLOPHON        top

       This page is part of thesystemtap (a tracing and live-system       analysis tool) project.  Information about the project can be       found at ⟨https://sourceware.org/systemtap/⟩.  If you have a bug       report for this manual page, send it to systemtap@sourceware.org.       This page was obtained from the project's upstream Git repository       ⟨git://sourceware.org/git/systemtap.git⟩ on 2025-08-11.  (At that       time, the date of the most recent commit that was found in the       repository was 2025-07-24.)  If you discover any rendering       problems in this HTML version of the page, or you believe there is       a better or more up-to-date source for the page, or you have       corrections or improvements to the information in this COLOPHON       (which isnot part of the original manual page), send a mail to       man-pages@man7.orgSTAPEX(3stap)

Pages that refer to this page:stap(1), stap-merge(1), stappaths(7), stapbpf(8), stapdyn(8), staprun(8), stap-server(8)

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