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Diffstat (limited to 'stapprobes.5.in')
| -rw-r--r-- | stapprobes.5.in | 48 |
1 files changed, 47 insertions, 1 deletions
diff --git a/stapprobes.5.in b/stapprobes.5.in index 099c071f..efefc1bf 100644 --- a/stapprobes.5.in +++ b/stapprobes.5.in @@ -235,6 +235,52 @@ $var[N] indexes into an array. The index is given with a literal number. +.SS PROCFS + +These probe points allow procfs "files" in +/proc/systemtap/MODNAME to be created, read and written +.RI ( MODNAME +is the name of the systemtap module). The +.I proc +filesystem is a pseudo-filesystem which is used an an interface to +kernel data structures. There are four probe point variants supported +by the translator: +.SAMPLE +procfs("PATH").read +procfs("PATH").write +procfs.read +procfs.write +.ESAMPLE +.I PATH +is the file name (relative to /proc/systemtap/MODNAME) to be created. +If no +.I PATH +is specified (as in the last two variants above), +.I PATH +defaults to "command". +.PP +When a user reads /proc/systemtap/MODNAME/PATH, the corresponding +procfs +.I read +probe is triggered. The string data to be read should be assigned to +a variable named +.IR $value , +like this: +.SAMPLE +procfs("PATH").read { $value = "100\\n" } +.ESAMPLE +.PP +When a user writes into /proc/systemtap/MODNAME/PATH, the +corresponding procfs +.I write +probe is triggered. The data the user wrote is available in the +string variable named +.IR $value , +like this: +.SAMPLE +procfs("PATH").write { printf("user wrote: %s", $value) } +.ESAMPLE + .SS MARKERS This family of probe points hooks up to static probing markers @@ -341,4 +387,4 @@ refers to the group of probe aliases with any name in the third position .IR stapprobes.socket (5), .IR stapprobes.tcp (5), .IR stapprobes.udp (5), - +.IR proc (5) |