NAME | LANGUAGE BASICS | PROBING | MORE EXAMPLES | SEE ALSO | COLOPHON |
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STAPEX(3stap) STAPEX(3stap)
stapex - systemtap examples
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.
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 ker‐ nel, use another listings mode. % stap -L 'kernel.function("*")'
The directory to find more examples can be found in the stappaths (7) manual page, and online at http://sourceware.org/systemtap/examples/
stap(1) stapprobes(3stap) stappaths(7)
This page is part of the systemtap (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 [email protected].
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/systemtap.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
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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 is not part of the original manual page), send a mail to
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STAPEX(3stap)
Pages that refer to this page: stap(1), stap-merge(1), stappaths(7), stapbpf(8), stapdyn(8), staprun(8), stap-server(8)