Provided by: systemtap-doc_1.6-1ubuntu1_all #### NAME

```       stapex - systemtap examples

```

#### LANGUAGEBASICS

```       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
delete evens
exit ()
}

probe end {
foreach (x+ in odds) {
printf ("odds[%d] = %d0, x, odds[x])
}
foreach (x in evens-) {
printf ("evens[%d] = %d0, x, evens[x])
}
}
This prints:
odds = 1
odds = 5
odds = 7
odds = 9
evens = 8
evens = 6
evens = 2
evens = 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("%d0, 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: %d0, fibonacci (11))
exit ()
}
Any larger number may exceed the MAXACTION or MAXNESTING limits, and result in an error.

```

#### PROBING

```       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("*")'

```

#### MOREEXAMPLES

```       The directory to find more examples can be found in the stappaths (7) manual page.

```

#### SEEALSO

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

STAPEX(3stap)
```