Sysdig User Guide
The simplest way to use sysdig is by invoking it without any argument. Doing this will cause sysdig to capture every event and write it to standard output, very much like strace does.
$ sysdig
34378 12:02:36.269753803 2 echo (7896) > close fd=3(/usr/lib/locale/locale-archive)
34379 12:02:36.269754164 2 echo (7896) < close res=0
34380 12:02:36.269781699 2 echo (7896) > fstat fd=1(/dev/pts/3)
34381 12:02:36.269783882 2 echo (7896) < fstat res=0
34382 12:02:36.269784970 2 echo (7896) > mmap
34383 12:02:36.269786575 2 echo (7896) < mmap
34384 12:02:36.269827674 2 echo (7896) > write fd=1(/dev/pts/3) size=12
34385 12:02:36.269839477 2 echo (7896) < write res=12 data=hello world.
34386 12:02:36.269843986 2 echo (7896) > close fd=1(/dev/pts/3)
34387 12:02:36.269844466 2 echo (7896) < close res=0
34388 12:02:36.269844816 2 echo (7896) > munmap
34389 12:02:36.269850803 2 echo (7896) < munmap
34390 12:02:36.269851915 2 echo (7896) > close fd=2(/dev/pts/3)
34391 12:02:36.269852314 2 echo (7896) < close res=0
By default, sysdig prints the information for each event on a single line, with the following format:
*%evt.num %evt.time %evt.cpu %proc.name (%thread.tid) %evt.dir %evt.type %evt.args
where:
- evt.num is the incremental event number
- evt.time is the event timestamp
- evt.cpu is the CPU number where the event was captured
- proc.name is the name of the process that generated the event
- thread.tid is the TID that generated the event, which corresponds to the PID for single thread processes
- evt.dir is the event direction, > for enter events and < for exit events
- evt.type is the name of the event, e.g. 'open' or 'read'
- evt.args is the list of event arguments. In case of system calls, these tend to correspond to the system call arguments, but that’s not always the case: some system call arguments are excluded for simplicity or performance reasons.
NOTE: Not all of the system calls are currently decoded by sysdig. Non-decoded system calls are still shown in the output, but with no arguments.
By looking at the output, you can immediately spot some key differences between this output and the strace one:
- For most system calls, sysdig shows two separate entries: an enter one (marked with a ‘>’) and an exit one (marked with a ‘<’). This makes it easier to follow the output in multi-process environments.
- File descriptors are resolved. This means that, whenever possible, the FD number is followed by a human-readable representation of the FD itself: the tuple for network connections, the name for files, and so on. The exact format used to render an FD is the following: num(<type>resolved_string) where:
- num is the FD number
- resolved_string is the resolved representation of the FD, e.g. 127.0.0.1:40370->127.0.0.1:80 for a TCP socket
- type is a single-letter-encoding of the fd type, and can be one of the following:
- f for files
- 4 for IPv4 sockets
- 6 for IPv6 sockets
- u for unix sockets
- s for signal FDs
- e for event FDs
- i for inotify FDs
- t for timer FDs
At this point you should be able to understand the basics of sysdig output, but of course sysdig is a powerful tool that can show a lot of interesting things. These two blog posts will give you more details and context:
Sysdig lets you save the captured events to disk so that they can be analyzed at a later time. The syntax is the following:
$ sysdig –w myfile.scap
If you want to limit the number of events saved to the file to 100, you can use the –n flag:
$ sysdig –n 100 –w myfile.scap
The -C command line flag lets you split a capture into files of a specific size. For example, use this to generate files that are 1MB in size:
sudo sysdig -C 1 -w dump.scap
You can combine the -C flag with the -W one to tell sysdig how many files to keep. For example, this command line captures events into files that are 1MB in size, and keeps only the last 5 files on disk:
sudo sysdig -C 1 -W 5 -w dump.scap
See here for more details on using file rotation for continuous capture.
Reading a previously saved capture file can be done with the –r flag:
$ sysdig –r myfile.scap
Note that sysdig saves a full snapshot of the OS in each capture file (running processes, open files, user names…), and this means that no information is lost when doing offline analysis. Note also that you can download a MAC and Windows version of sysdig. They won’t be able to do live capture, but they can be used to analyze capture files that have been gathered under Linux.
Now that we took care of the basics, let’s start having some fun. Sysdig’s filtering system is powerful and versatile, and is designed to look for needles in a haystack. Filters are specified at the end of the command line, like in tcpdump, and can be applied to both a live capture or a capture file. For example, let’s look at the activity of a specific command, in this case cat:
$ ./sysdig proc.name=cat
21368 13:10:15.384878134 1 cat (8298) < execve res=0 exe=cat args=index.html. tid=8298(cat) pid=8298(cat) ptid=1978(bash) cwd=/root fdlimit=1024
21371 13:10:15.384948635 1 cat (8298) > brk size=0
21372 13:10:15.384949909 1 cat (8298) < brk res=10665984
21373 13:10:15.384976208 1 cat (8298) > mmap
21374 13:10:15.384979452 1 cat (8298) < mmap
21375 13:10:15.384990980 1 cat (8298) > access
21376 13:10:15.384999211 1 cat (8298) < access
21377 13:10:15.385008602 1 cat (8298) > open
21378 13:10:15.385014374 1 cat (8298) < open fd=3(/etc/ld.so.cache) name=/etc/ld.so.cache flags=0(O_NONE) mode=0
21379 13:10:15.385015508 1 cat (8298) > fstat fd=3(/etc/ld.so.cache)
21380 13:10:15.385016588 1 cat (8298) < fstat res=0
21381 13:10:15.385017033 1 cat (8298) > mmap
21382 13:10:15.385019763 1 cat (8298) < mmap
21383 13:10:15.385020047 1 cat (8298) > close fd=3(/etc/ld.so.cache)
21384 13:10:15.385020556 1 cat (8298) < close res=0
As you can see, sysdig doesn’t attach to processes. It just captures everything and then lets you filter out what you’re not interested in. Filter statements can use comparison operators (=, !=, <, <=, >, >=, contains, icontains, in, exists) and can be combined using Boolean operators (and, or and not) and parentheses. For example
$ sysdig proc.name=cat or proc.name=vi
captures the activity of both cat and vi, while
$ sysdig proc.name!=cat and evt.type=open
shows all the files that are opened by programs that are not cat.
Some filters use external information such as dns information to match events and filtering expressions. See this page for more detail.
Filter fields are expressed as 'class.field'. A quick way to get a list of the available classes and the fields they include is
$ sysdig -l
As a reference, here’s a list of the fields you can use (Note: The list changes with every new release, so make sure to use the program for the most updated one):
----------------------
Field Class: fd
fd.num the unique number identifying the file descriptor.
fd.type type of FD. Can be 'file', 'directory', 'ipv4', 'ipv6', 'unix',
'pipe', 'event', 'signalfd', 'eventpoll', 'inotify' or 'signal
fd'.
fd.typechar type of FD as a single character. Can be 'f' for file, 4 for IP
v4 socket, 6 for IPv6 socket, 'u' for unix socket, p for pipe,
'e' for eventfd, 's' for signalfd, 'l' for eventpoll, 'i' for i
notify, 'o' for unknown.
fd.name FD full name. If the fd is a file, this field contains the full
path. If the FD is a socket, this field contain the connection
tuple.
fd.directory If the fd is a file, the directory that contains it.
fd.filename If the fd is a file, the filename without the path.
fd.ip (FILTER ONLY) matches the ip address (client or server) of the
fd.
fd.cip client IP address.
fd.sip server IP address.
fd.lip local IP address.
fd.rip remote IP address.
fd.port (FILTER ONLY) matches the port (either client or server) of the
fd.
fd.cport for TCP/UDP FDs, the client port.
fd.sport for TCP/UDP FDs, server port.
fd.lport for TCP/UDP FDs, the local port.
fd.rport for TCP/UDP FDs, the remote port.
fd.l4proto the IP protocol of a socket. Can be 'tcp', 'udp', 'icmp' or 'ra
w'.
fd.sockfamily the socket family for socket events. Can be 'ip' or 'unix'.
fd.is_server 'true' if the process owning this FD is the server endpoint in
the connection.
fd.uid a unique identifier for the FD, created by chaining the FD numb
er and the thread ID.
fd.containername
chaining of the container ID and the FD name. Useful when tryin
g to identify which container an FD belongs to.
fd.containerdirectory
chaining of the container ID and the directory name. Useful whe
n trying to identify which container a directory belongs to.
fd.proto (FILTER ONLY) matches the protocol (either client or server) of
the fd.
fd.cproto for TCP/UDP FDs, the client protocol.
fd.sproto for TCP/UDP FDs, server protocol.
fd.lproto for TCP/UDP FDs, the local protocol.
fd.rproto for TCP/UDP FDs, the remote protocol.
fd.net (FILTER ONLY) matches the IP network (client or server) of the
fd.
fd.cnet (FILTER ONLY) matches the client IP network of the fd.
fd.snet (FILTER ONLY) matches the server IP network of the fd.
fd.lnet (FILTER ONLY) matches the local IP network of the fd.
fd.rnet (FILTER ONLY) matches the remote IP network of the fd.
fd.connected for TCP/UDP FDs, 'true' if the socket is connected.
fd.name_changed True when an event changes the name of an fd used by this event
. This can occur in some cases such as udp connections where th
e connection tuple changes.
fd.cip.name Domain name associated with the client IP address.
fd.sip.name Domain name associated with the server IP address.
fd.lip.name Domain name associated with the local IP address.
fd.rip.name Domain name associated with the remote IP address.
----------------------
Field Class: process
proc.pid the id of the process generating the event.
proc.exe the first command line argument (usually the executable name or
a custom one).
proc.name the name (excluding the path) of the executable generating the
event.
proc.args the arguments passed on the command line when starting the proc
ess generating the event.
proc.env the environment variables of the process generating the event.
proc.cmdline full process command line, i.e. proc.name + proc.args.
proc.exeline full process command line, with exe as first argument, i.e. pro
c.exe + proc.args.
proc.cwd the current working directory of the event.
proc.nthreads the number of threads that the process generating the event cur
rently has, including the main process thread.
proc.nchilds the number of child threads that the process generating the eve
nt currently has. This excludes the main process thread.
proc.ppid the pid of the parent of the process generating the event.
proc.pname the name (excluding the path) of the parent of the process gene
rating the event.
proc.pcmdline the full command line (proc.name + proc.args) of the parent of
the process generating the event.
proc.apid the pid of one of the process ancestors. E.g. proc.apid[1] retu
rns the parent pid, proc.apid[2] returns the grandparent pid, a
nd so on. proc.apid[0] is the pid of the current process. proc.
apid without arguments can be used in filters only and matches
any of the process ancestors, e.g. proc.apid=1234.
proc.aname the name (excluding the path) of one of the process ancestors.
E.g. proc.aname[1] returns the parent name, proc.aname[2] retur
ns the grandparent name, and so on. proc.aname[0] is the name o
f the current process. proc.aname without arguments can be used
in filters only and matches any of the process ancestors, e.g.
proc.aname=bash.
proc.loginshellid
the pid of the oldest shell among the ancestors of the current
process, if there is one. This field can be used to separate di
fferent user sessions, and is useful in conjunction with chisel
s like spy_user.
proc.duration number of nanoseconds since the process started.
proc.fdopencount
number of open FDs for the process
proc.fdlimit maximum number of FDs the process can open.
proc.fdusage the ratio between open FDs and maximum available FDs for the pr
ocess.
proc.vmsize total virtual memory for the process (as kb).
proc.vmrss resident non-swapped memory for the process (as kb).
proc.vmswap swapped memory for the process (as kb).
thread.pfmajor number of major page faults since thread start.
thread.pfminor number of minor page faults since thread start.
thread.tid the id of the thread generating the event.
thread.ismain 'true' if the thread generating the event is the main one in th
e process.
thread.exectime CPU time spent by the last scheduled thread, in nanoseconds. Ex
ported by switch events only.
thread.totexectime
Total CPU time, in nanoseconds since the beginning of the captu
re, for the current thread. Exported by switch events only.
thread.cgroups all the cgroups the thread belongs to, aggregated into a single
string.
thread.cgroup the cgroup the thread belongs to, for a specific subsystem. E.g
. thread.cgroup.cpuacct.
thread.vtid the id of the thread generating the event as seen from its curr
ent PID namespace.
proc.vpid the id of the process generating the event as seen from its cur
rent PID namespace.
thread.cpu the CPU consumed by the thread in the last second.
thread.cpu.user the user CPU consumed by the thread in the last second.
thread.cpu.system
the system CPU consumed by the thread in the last second.
thread.vmsize For the process main thread, this is the total virtual memory f
or the process (as kb). For the other threads, this field is ze
ro.
thread.vmrss For the process main thread, this is the resident non-swapped m
emory for the process (as kb). For the other threads, this fiel
d is zero.
proc.sid the session id of the process generating the event.
proc.sname the name of the current process's session leader. This is eithe
r the process with pid=proc.sid or the eldest ancestor that has
the same sid as the current process.
proc.tty The controlling terminal of the process. 0 for processes withou
t a terminal.
proc.exepath The full executable path of the process.
proc.vpgid the process group id of the process generating the event, as se
en from its current PID namespace.
----------------------
Field Class: evt
evt.num event number.
evt.time event timestamp as a time string that includes the nanosecond p
art.
evt.time.s event timestamp as a time string with no nanoseconds.
evt.datetime event timestamp as a time string that includes the date.
evt.rawtime absolute event timestamp, i.e. nanoseconds from epoch.
evt.rawtime.s integer part of the event timestamp (e.g. seconds since epoch).
evt.rawtime.ns fractional part of the absolute event timestamp.
evt.reltime number of nanoseconds from the beginning of the capture.
evt.reltime.s number of seconds from the beginning of the capture.
evt.reltime.ns fractional part (in ns) of the time from the beginning of the c
apture.
evt.latency delta between an exit event and the correspondent enter event,
in nanoseconds.
evt.latency.s integer part of the event latency delta.
evt.latency.ns fractional part of the event latency delta.
evt.latency.human
delta between an exit event and the correspondent enter event,
as a human readable string (e.g. 10.3ms).
evt.deltatime delta between this event and the previous event, in nanoseconds
.
evt.deltatime.s integer part of the delta between this event and the previous e
vent.
evt.deltatime.ns
fractional part of the delta between this event and the previou
s event.
evt.outputtime this depends on -t param, default is %evt.time ('h').
evt.dir event direction can be either '>' for enter events or '<' for e
xit events.
evt.type The name of the event (e.g. 'open').
evt.type.is allows one to specify an event type, and returns 1 for events t
hat are of that type. For example, evt.type.is.open returns 1 f
or open events, 0 for any other event.
syscall.type For system call events, the name of the system call (e.g. 'open
'). Unset for other events (e.g. switch or sysdig internal even
ts). Use this field instead of evt.type if you need to make sur
e that the filtered/printed value is actually a system call.
evt.category The event category. Example values are 'file' (for file operati
ons like open and close), 'net' (for network operations like so
cket and bind), memory (for things like brk or mmap), and so on
.
evt.cpu number of the CPU where this event happened.
evt.args all the event arguments, aggregated into a single string.
evt.arg one of the event arguments specified by name or by number. Some
events (e.g. return codes or FDs) will be converted into a tex
t representation when possible. E.g. 'evt.arg.fd' or 'evt.arg[0
]'.
evt.rawarg one of the event arguments specified by name. E.g. 'evt.rawarg.
fd'.
evt.info for most events, this field returns the same value as evt.args.
However, for some events (like writes to /dev/log) it provides
higher level information coming from decoding the arguments.
evt.buffer the binary data buffer for events that have one, like read(), r
ecvfrom(), etc. Use this field in filters with 'contains' to se
arch into I/O data buffers.
evt.buflen the length of the binary data buffer for events that have one,
like read(), recvfrom(), etc.
evt.res event return value, as a string. If the event failed, the resul
t is an error code string (e.g. 'ENOENT'), otherwise the result
is the string 'SUCCESS'.
evt.rawres event return value, as a number (e.g. -2). Useful for range com
parisons.
evt.failed 'true' for events that returned an error status.
evt.is_io 'true' for events that read or write to FDs, like read(), send,
recvfrom(), etc.
evt.is_io_read 'true' for events that read from FDs, like read(), recv(), recv
from(), etc.
evt.is_io_write 'true' for events that write to FDs, like write(), send(), etc.
evt.io_dir 'r' for events that read from FDs, like read(); 'w' for events
that write to FDs, like write().
evt.is_wait 'true' for events that make the thread wait, e.g. sleep(), sele
ct(), poll().
evt.wait_latency
for events that make the thread wait (e.g. sleep(), select(), p
oll()), this is the time spent waiting for the event to return,
in nanoseconds.
evt.is_syslog 'true' for events that are writes to /dev/log.
evt.count This filter field always returns 1 and can be used to count eve
nts from inside chisels.
evt.count.error This filter field returns 1 for events that returned with an er
ror, and can be used to count event failures from inside chisel
s.
evt.count.error.file
This filter field returns 1 for events that returned with an er
ror and are related to file I/O, and can be used to count event
failures from inside chisels.
evt.count.error.net
This filter field returns 1 for events that returned with an er
ror and are related to network I/O, and can be used to count ev
ent failures from inside chisels.
evt.count.error.memory
This filter field returns 1 for events that returned with an er
ror and are related to memory allocation, and can be used to co
unt event failures from inside chisels.
evt.count.error.other
This filter field returns 1 for events that returned with an er
ror and are related to none of the previous categories, and can
be used to count event failures from inside chisels.
evt.count.exit This filter field returns 1 for exit events, and can be used to
count single events from inside chisels.
evt.around (FILTER ONLY) Accepts the event if it's around the specified ti
me interval. The syntax is evt.around[T]=D, where T is the valu
e returned by %evt.rawtime for the event and D is a delta in mi
lliseconds. For example, evt.around[1404996934793590564]=1000 w
ill return the events with timestamp with one second before the
timestamp and one second after it, for a total of two seconds
of capture.
evt.abspath Absolute path calculated from dirfd and name during syscalls li
ke renameat and symlinkat. Use 'evt.abspath.src' or 'evt.abspat
h.dst' for syscalls that support multiple paths.
evt.is_open_read
'true' for open/openat events where the path was opened for rea
ding
evt.is_open_write
'true' for open/openat events where the path was opened for wri
ting
----------------------
Field Class: user
user.uid user ID.
user.name user name.
user.homedir home directory of the user.
user.shell user's shell.
user.loginuid audit user id (auid).
user.loginname audit user name (auid).
----------------------
Field Class: group
group.gid group ID.
group.name group name.
----------------------
Field Class: syslog
syslog.facility.str
facility as a string.
syslog.facility facility as a number (0-23).
syslog.severity.str
severity as a string. Can have one of these values: emerg, aler
t, crit, err, warn, notice, info, debug
syslog.severity severity as a number (0-7).
syslog.message message sent to syslog.
----------------------
Field Class: container
container.id the container id.
container.name the container name.
container.image the container image name (e.g. sysdig/sysdig:latest for docker,
).
container.image.id
the container image id (e.g. 6f7e2741b66b).
container.type the container type, eg: docker or rkt
container.privileged
true for containers running as privileged, false otherwise
container.mounts
A space-separated list of mount information. Each item in the l
ist has the format <source>:<dest>:<mode>:<rdrw>:<propagation>
container.mount Information about a single mount, specified by number (e.g. con
tainer.mount[0]) or mount source (container.mount[/usr/local]).
The pathname can be a glob (container.mount[/usr/local/*]), in
which case the first matching mount will be returned. The info
rmation has the format <source>:<dest>:<mode>:<rdrw>:<propagati
on>. If there is no mount with the specified index or matching
the provided source, returns the string "none" instead of a NUL
L value.
container.mount.source
the mount source, specified by number (e.g. container.mount.sou
rce[0]) or mount destination (container.mount.source[/host/lib/
modules]). The pathname can be a glob.
container.mount.dest
the mount destination, specified by number (e.g. container.moun
t.dest[0]) or mount source (container.mount.dest[/lib/modules])
. The pathname can be a glob.
container.mount.mode
the mount mode, specified by number (e.g. container.mount.mode[
0]) or mount source (container.mount.mode[/usr/local]). The pat
hname can be a glob.
container.mount.rdwr
the mount rdwr value, specified by number (e.g. container.mount
.rdwr[0]) or mount source (container.mount.rdwr[/usr/local]). T
he pathname can be a glob.
container.mount.propagation
the mount propagation value, specified by number (e.g. containe
r.mount.propagation[0]) or mount source (container.mount.propag
ation[/usr/local]). The pathname can be a glob.
container.image.repository
the container image repository (e.g. sysdig/sysdig).
container.image.tag
the container image tag (e.g. stable, latest).
container.image.digest
the container image registry digest (e.g. sha256:d977378f890d44
5c15e51795296e4e5062f109ce6da83e0a355fc4ad8699d27).
----------------------
Field Class: fdlist
fdlist.nums for poll events, this is a comma-separated list of the FD numbe
rs in the 'fds' argument, returned as a string.
fdlist.names for poll events, this is a comma-separated list of the FD names
in the 'fds' argument, returned as a string.
fdlist.cips for poll events, this is a comma-separated list of the client I
P addresses in the 'fds' argument, returned as a string.
fdlist.sips for poll events, this is a comma-separated list of the server I
P addresses in the 'fds' argument, returned as a string.
fdlist.cports for TCP/UDP FDs, for poll events, this is a comma-separated lis
t of the client TCP/UDP ports in the 'fds' argument, returned a
s a string.
fdlist.sports for poll events, this is a comma-separated list of the server T
CP/UDP ports in the 'fds' argument, returned as a string.
----------------------
Field Class: k8s
k8s.pod.name Kubernetes pod name.
k8s.pod.id Kubernetes pod id.
k8s.pod.label Kubernetes pod label. E.g. 'k8s.pod.label.foo'.
k8s.pod.labels Kubernetes pod comma-separated key/value labels. E.g. 'foo1:bar
1,foo2:bar2'.
k8s.rc.name Kubernetes replication controller name.
k8s.rc.id Kubernetes replication controller id.
k8s.rc.label Kubernetes replication controller label. E.g. 'k8s.rc.label.foo
'.
k8s.rc.labels Kubernetes replication controller comma-separated key/value lab
els. E.g. 'foo1:bar1,foo2:bar2'.
k8s.svc.name Kubernetes service name (can return more than one value, concat
enated).
k8s.svc.id Kubernetes service id (can return more than one value, concaten
ated).
k8s.svc.label Kubernetes service label. E.g. 'k8s.svc.label.foo' (can return
more than one value, concatenated).
k8s.svc.labels Kubernetes service comma-separated key/value labels. E.g. 'foo1
:bar1,foo2:bar2'.
k8s.ns.name Kubernetes namespace name.
k8s.ns.id Kubernetes namespace id.
k8s.ns.label Kubernetes namespace label. E.g. 'k8s.ns.label.foo'.
k8s.ns.labels Kubernetes namespace comma-separated key/value labels. E.g. 'fo
o1:bar1,foo2:bar2'.
k8s.rs.name Kubernetes replica set name.
k8s.rs.id Kubernetes replica set id.
k8s.rs.label Kubernetes replica set label. E.g. 'k8s.rs.label.foo'.
k8s.rs.labels Kubernetes replica set comma-separated key/value labels. E.g. '
foo1:bar1,foo2:bar2'.
k8s.deployment.name
Kubernetes deployment name.
k8s.deployment.id
Kubernetes deployment id.
k8s.deployment.label
Kubernetes deployment label. E.g. 'k8s.rs.label.foo'.
k8s.deployment.labels
Kubernetes deployment comma-separated key/value labels. E.g. 'f
oo1:bar1,foo2:bar2'.
----------------------
Field Class: mesos
mesos.task.name Mesos task name.
mesos.task.id Mesos task id.
mesos.task.label
Mesos task label. E.g. 'mesos.task.label.foo'.
mesos.task.labels
Mesos task comma-separated key/value labels. E.g. 'foo1:bar1,fo
o2:bar2'.
mesos.framework.name
Mesos framework name.
mesos.framework.id
Mesos framework id.
marathon.app.name
Marathon app name.
marathon.app.id Marathon app id.
marathon.app.label
Marathon app label. E.g. 'marathon.app.label.foo'.
marathon.app.labels
Marathon app comma-separated key/value labels. E.g. 'foo1:bar1,
foo2:bar2'.
marathon.group.name
Marathon group name.
marathon.group.id
Marathon group id.
----------------------
Field Class: span
span.id ID of the span. This is a unique identifier that is used to mat
ch the enter and exit tracer events for this span. It can also
be used to match different spans belonging to a trace.
span.time time of the span's enter tracer as a human readable string that
includes the nanosecond part.
span.ntags number of tags that this span has.
span.nargs number of arguments that this span has.
span.tags dot-separated list of all of the span's tags.
span.tag one of the span's tags, specified by 0-based offset, e.g. 'span
.tag[1]'. You can use a negative offset to pick elements from t
he end of the tag list. For example, 'span.tag[-1]' returns the
last tag.
span.args comma-separated list of the span's arguments.
span.arg one of the span arguments, specified by name or by 0-based offs
et. E.g. 'span.arg.xxx' or 'span.arg[1]'. You can use a negativ
e offset to pick elements from the end of the tag list. For exa
mple, 'span.arg[-1]' returns the last argument.
span.enterargs comma-separated list of the span's enter tracer event arguments
. For enter tracers, this is the same as evt.args. For exit tra
cers, this is the evt.args of the corresponding enter tracer.
span.enterarg one of the span's enter arguments, specified by name or by 0-ba
sed offset. For enter tracer events, this is the same as evt.ar
g. For exit tracer events, this is the evt.arg of the correspon
ding enter event.
span.duration delta between this span's exit tracer event and the enter trace
r event.
span.duration.human
delta between this span's exit tracer event and the enter event
, as a human readable string (e.g. 10.3ms).
----------------------
Field Class: evtin
evtin.span.id accepts all the events that are between the enter and exit trac
ers of the spans with the given ID and are generated by the sam
e thread that generated the tracers.
evtin.span.ntags
accepts all the events that are between the enter and exit trac
ers of the spans with the given number of tags and are generate
d by the same thread that generated the tracers.
evtin.span.nargs
accepts all the events that are between the enter and exit trac
ers of the spans with the given number of arguments and are gen
erated by the same thread that generated the tracers.
evtin.span.tags accepts all the events that are between the enter and exit trac
ers of the spans with the given tags and are generated by the s
ame thread that generated the tracers.
evtin.span.tag accepts all the events that are between the enter and exit trac
ers of the spans with the given tag and are generated by the sa
me thread that generated the tracers. See the description of sp
an.tag for information about the syntax accepted by this field.
evtin.span.args accepts all the events that are between the enter and exit trac
ers of the spans with the given arguments and are generated by
the same thread that generated the tracers.
evtin.span.arg accepts all the events that are between the enter and exit trac
ers of the spans with the given argument and are generated by t
he same thread that generated the tracers. See the description
of span.arg for information about the syntax accepted by this f
ield.
evtin.span.p.id same as evtin.span.id, but also accepts events generated by oth
er threads in the same process that produced the span.
evtin.span.p.ntags
same as evtin.span.ntags, but also accepts events generated by
other threads in the same process that produced the span.
evtin.span.p.nargs
same as evtin.span.nargs, but also accepts events generated by
other threads in the same process that produced the span.
evtin.span.p.tags
same as evtin.span.tags, but also accepts events generated by o
ther threads in the same process that produced the span.
evtin.span.p.tag
same as evtin.span.tag, but also accepts events generated by ot
her threads in the same process that produced the span.
evtin.span.p.args
same as evtin.span.args, but also accepts events generated by o
ther threads in the same process that produced the span.
evtin.span.p.arg
same as evtin.span.arg, but also accepts events generated by ot
her threads in the same process that produced the span.
evtin.span.s.id same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.ntags
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.nargs
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.tags
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.tag
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.args
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.s.arg
same as evtin.span.id, but also accepts events generated by the
script that produced the span, i.e. by the processes whose par
ent PID is the same as the one of the process generating the sp
an.
evtin.span.m.id same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.ntags
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.nargs
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.tags
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.tag
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.args
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
evtin.span.m.arg
same as evtin.span.id, but accepts all the events generated on
the machine during the span, including other threads and other
processes.
As you can see, enough to do plenty of creative digging. For example, thanks to the fact that sysdig resolves file descriptors, you can do stuff like this:
$ sysdig evt.type=accept and proc.name!=apache
to see the incoming network connections received by processes other than apache.
But that’s not all.
There are a couple of special fields, evt.arg and evt.rawarg, that deserve additional explanation. Every event that sysdig captures has a type (e.g. 'open', 'read'...), and a set of parameters (e.g. 'fd', 'name'...) that are encoded using a standardize type system. I know this sounds boring, so let’s just talk about the benefits of it: any parameter of any event can be used in filters. For example this command line shows the programs that are run by interactive users:
$ sysdig evt.type=execve and evt.arg.ptid=bash
The filter accepts the execve system calls (which are used to execute programs), but only if the parent process name is ‘bash’. The difference between evt.arg and event.rawarg is that the second doesn’t do resolution of PIDs, FDs, error codes, etc, and leaves the argument in its raw numeric form. For example, you can use
$ sysdig evt.arg.res=ENOENT
To filter on a specific I/O error code or, since error codes are negative, this
$ sysdig " evt.rawarg.res<0 or evt.rawarg.fd<0"
will give you all the system calls that produced errors. To get a list of all the events you can use in your filters, plus their parameters, type
$ sysdig –L
And, for your reference, here’s the list, where ‘>’ indicates an enter event and ‘<’ indicates an exit event (Note: The list changes with every new release, so make sure to use the program for the most updated one):
> syscall(SYSCALLID ID, UINT16 nativeID)
< syscall(SYSCALLID ID)
> open()
< open(FD fd, FSPATH name, FLAGS32 flags, UINT32 mode)
> close(FD fd)
< close(ERRNO res)
> read(FD fd, UINT32 size)
< read(ERRNO res, BYTEBUF data)
> write(FD fd, UINT32 size)
< write(ERRNO res, BYTEBUF data)
> socket(FLAGS32 domain, UINT32 type, UINT32 proto)
< socket(FD fd)
> bind(FD fd)
< bind(ERRNO res, SOCKADDR addr)
> connect(FD fd)
< connect(ERRNO res, SOCKTUPLE tuple)
> listen(FD fd, UINT32 backlog)
< listen(ERRNO res)
> send(FD fd, UINT32 size)
< send(ERRNO res, BYTEBUF data)
> sendto(FD fd, UINT32 size, SOCKTUPLE tuple)
< sendto(ERRNO res, BYTEBUF data)
> recv(FD fd, UINT32 size)
< recv(ERRNO res, BYTEBUF data)
> recvfrom(FD fd, UINT32 size)
< recvfrom(ERRNO res, BYTEBUF data, SOCKTUPLE tuple)
> shutdown(FD fd, FLAGS8 how)
< shutdown(ERRNO res)
> getsockname()
< getsockname()
> getpeername()
< getpeername()
> socketpair(FLAGS32 domain, UINT32 type, UINT32 proto)
< socketpair(ERRNO res, FD fd1, FD fd2, UINT64 source, UINT64 peer)
> setsockopt()
< setsockopt()
> getsockopt()
< getsockopt()
> sendmsg(FD fd, UINT32 size, SOCKTUPLE tuple)
< sendmsg(ERRNO res, BYTEBUF data)
> sendmmsg()
< sendmmsg()
> recvmsg(FD fd)
< recvmsg(ERRNO res, UINT32 size, BYTEBUF data, SOCKTUPLE tuple)
> recvmmsg()
< recvmmsg()
> creat()
< creat(FD fd, FSPATH name, UINT32 mode)
> pipe()
< pipe(ERRNO res, FD fd1, FD fd2, UINT64 ino)
> eventfd(UINT64 initval, FLAGS32 flags)
< eventfd(FD res)
> futex(UINT64 addr, FLAGS16 op, UINT64 val)
< futex(ERRNO res)
> stat()
< stat(ERRNO res, FSPATH path)
> lstat()
< lstat(ERRNO res, FSPATH path)
> fstat(FD fd)
< fstat(ERRNO res)
> stat64()
< stat64(ERRNO res, FSPATH path)
> lstat64()
< lstat64(ERRNO res, FSPATH path)
> fstat64(FD fd)
< fstat64(ERRNO res)
> epoll_wait(ERRNO maxevents)
< epoll_wait(ERRNO res)
> poll(FDLIST fds, INT64 timeout)
< poll(ERRNO res, FDLIST fds)
> select()
< select(ERRNO res)
> select()
< select(ERRNO res)
> lseek(FD fd, UINT64 offset, FLAGS8 whence)
< lseek(ERRNO res)
> llseek(FD fd, UINT64 offset, FLAGS8 whence)
< llseek(ERRNO res)
> getcwd()
< getcwd(ERRNO res, CHARBUF path)
> chdir()
< chdir(ERRNO res, CHARBUF path)
> fchdir(FD fd)
< fchdir(ERRNO res)
> mkdir(FSPATH path, UINT32 mode)
< mkdir(ERRNO res)
> rmdir(FSPATH path)
< rmdir(ERRNO res)
> openat(FD dirfd, CHARBUF name, FLAGS32 flags, UINT32 mode)
< openat(FD fd)
> link(FSPATH oldpath, FSPATH newpath)
< link(ERRNO res)
> linkat(FD olddir, CHARBUF oldpath, FD newdir, CHARBUF newpath)
< linkat(ERRNO res)
> unlink(FSPATH path)
< unlink(ERRNO res)
> unlinkat(FD dirfd, CHARBUF name)
< unlinkat(ERRNO res)
> pread(FD fd, UINT32 size, UINT64 pos)
< pread(ERRNO res, BYTEBUF data)
> pwrite(FD fd, UINT32 size, UINT64 pos)
< pwrite(ERRNO res, BYTEBUF data)
> readv(FD fd)
< readv(ERRNO res, UINT32 size, BYTEBUF data)
> writev(FD fd, UINT32 size)
< writev(ERRNO res, BYTEBUF data)
> preadv(FD fd, UINT64 pos)
< preadv(ERRNO res, UINT32 size, BYTEBUF data)
> pwritev(FD fd, UINT32 size, UINT64 pos)
< pwritev(ERRNO res, BYTEBUF data)
> dup(FD fd)
< dup(FD res)
> signalfd(FD fd, UINT32 mask, FLAGS8 flags)
< signalfd(FD res)
> kill(PID pid, SIGTYPE sig)
< kill(ERRNO res)
> tkill(PID tid, SIGTYPE sig)
< tkill(ERRNO res)
> tgkill(PID pid, PID tid, SIGTYPE sig)
< tgkill(ERRNO res)
> nanosleep(RELTIME interval)
< nanosleep(ERRNO res)
> timerfd_create(UINT8 clockid, FLAGS8 flags)
< timerfd_create(FD res)
> inotify_init(FLAGS8 flags)
< inotify_init(FD res)
> getrlimit(FLAGS8 resource)
< getrlimit(ERRNO res, INT64 cur, INT64 max)
> setrlimit(FLAGS8 resource)
< setrlimit(ERRNO res, INT64 cur, INT64 max)
> prlimit(PID pid, FLAGS8 resource)
< prlimit(ERRNO res, INT64 newcur, INT64 newmax, INT64 oldcur, INT64 oldmax)
> fcntl(FD fd, FLAGS8 cmd)
< fcntl(FD res)
> switch(PID next, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap)
> brk(UINT64 addr)
< brk(UINT64 res, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap)
> mmap(UINT64 addr, UINT64 length, FLAGS32 prot, FLAGS32 flags, FD fd, UINT64 offset)
< mmap(UINT64 res, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap)
> mmap2(UINT64 addr, UINT64 length, FLAGS32 prot, FLAGS32 flags, FD fd, UINT64 pgoffset)
< mmap2(UINT64 res, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap)
> munmap(UINT64 addr, UINT64 length)
< munmap(ERRNO res, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap)
> splice(FD fd_in, FD fd_out, UINT64 size, FLAGS32 flags)
< splice(ERRNO res)
> ptrace(FLAGS16 request, PID pid)
< ptrace(ERRNO res, DYNAMIC addr, DYNAMIC data)
> ioctl(FD fd, UINT64 request, UINT64 argument)
< ioctl(ERRNO res)
> rename()
< rename(ERRNO res, FSPATH oldpath, FSPATH newpath)
> renameat()
< renameat(ERRNO res, FD olddirfd, CHARBUF oldpath, FD newdirfd, CHARBUF newpath)
> symlink()
< symlink(ERRNO res, CHARBUF target, FSPATH linkpath)
> symlinkat()
< symlinkat(ERRNO res, CHARBUF target, FD linkdirfd, CHARBUF linkpath)
> procexit(ERRNO status)
> sendfile(FD out_fd, FD in_fd, UINT64 offset, UINT64 size)
< sendfile(ERRNO res, UINT64 offset)
> quotactl(FLAGS16 cmd, FLAGS8 type, UINT32 id, FLAGS8 quota_fmt)
> setresuid(UID ruid, UID euid, UID suid)
< setresuid(ERRNO res)
> setresgid(GID rgid, GID egid, GID sgid)
< setresgid(ERRNO res)
> setuid(UID uid)
< setuid(ERRNO res)
> setgid(GID gid)
< setgid(ERRNO res)
> getuid()
< getuid(UID uid)
> geteuid()
< geteuid(UID euid)
> getgid()
< getgid(GID gid)
> getegid()
< getegid(GID egid)
> getresuid()
< getresuid(ERRNO res, UID ruid, UID euid, UID suid)
> getresgid()
< getresgid(ERRNO res, GID rgid, GID egid, GID sgid)
> clone()
< clone(PID res, CHARBUF exe, BYTEBUF args, PID tid, PID pid, PID ptid, CHARBUF cwd, INT64 fdlimit, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap, CHARBUF comm, BYTEBUF cgroups, FLAGS32 flags, UINT32 uid, UINT32 gid, PID vtid, PID vpid)
> fork()
< fork(PID res, CHARBUF exe, BYTEBUF args, PID tid, PID pid, PID ptid, CHARBUF cwd, INT64 fdlimit, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap, CHARBUF comm, BYTEBUF cgroups, FLAGS32 flags, UINT32 uid, UINT32 gid, PID vtid, PID vpid)
> vfork()
< vfork(PID res, CHARBUF exe, BYTEBUF args, PID tid, PID pid, PID ptid, CHARBUF cwd, INT64 fdlimit, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap, CHARBUF comm, BYTEBUF cgroups, FLAGS32 flags, UINT32 uid, UINT32 gid, PID vtid, PID vpid)
> execve()
< execve(ERRNO res, CHARBUF exe, BYTEBUF args, PID tid, PID pid, PID ptid, CHARBUF cwd, UINT64 fdlimit, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap, CHARBUF comm, BYTEBUF cgroups, BYTEBUF env)
> signaldeliver(PID spid, PID dpid, SIGTYPE sig)
> getdents(FD fd)
< getdents(ERRNO res)
> getdents64(FD fd)
< getdents64(ERRNO res)
> setns(FD fd, FLAGS32 nstype)
< setns(ERRNO res)
> flock(FD fd, FLAGS32 operation)
< flock(ERRNO res)
> cpu_hotplug(UINT32 cpu, UINT32 action)
> accept()
< accept(FD fd, SOCKTUPLE tuple, UINT8 queuepct, UINT32 queuelen, UINT32 queuemax)
> accept(INT32 flags)
< accept(FD fd, SOCKTUPLE tuple, UINT8 queuepct, UINT32 queuelen, UINT32 queuemax)
> semop(INT32 semid)
< semop(ERRNO res, UINT32 nsops, UINT16 sem_num_0, INT16 sem_op_0, FLAGS16 sem_flg_0, UINT16 sem_num_1, INT16 sem_op_1, FLAGS16 sem_flg_1)
> semctl(INT32 semid, INT32 semnum, FLAGS16 cmd, INT32 val)
< semctl(ERRNO res)
> ppoll(FDLIST fds, RELTIME timeout, SIGSET sigmask)
< ppoll(ERRNO res, FDLIST fds)
> mount(FLAGS32 flags)
< mount(ERRNO res, CHARBUF dev, FSPATH dir, CHARBUF type)
> umount(FLAGS32 flags)
< umount(ERRNO res, FSPATH name)
> semget(INT32 key, INT32 nsems, FLAGS32 semflg)
< semget(ERRNO res)
> access(FLAGS32 mode)
< access(ERRNO res, FSPATH name)
> chroot()
< chroot(ERRNO res, FSPATH path)
> tracer(INT64 id, CHARBUFARRAY tags, CHARBUF_PAIR_ARRAY args)
< tracer(INT64 id, CHARBUFARRAY tags, CHARBUF_PAIR_ARRAY args)
> setsid()
< setsid(PID res)
> mkdir(UINT32 mode)
< mkdir(ERRNO res, FSPATH path)
> rmdir()
< rmdir(ERRNO res, FSPATH path)
> notification(CHARBUF id, CHARBUF desc)
> execve()
< execve(ERRNO res, CHARBUF exe, BYTEBUF args, PID tid, PID pid, PID ptid, CHARBUF cwd, UINT64 fdlimit, UINT64 pgft_maj, UINT64 pgft_min, UINT32 vm_size, UINT32 vm_rss, UINT32 vm_swap, CHARBUF comm, BYTEBUF cgroups, BYTEBUF env, INT32 tty)
> unshare(FLAGS32 flags)
< unshare(ERRNO res)
Did you take some time to experiment with filtering and filter fields? Good, because now we’re going to learn how to use the same fields to customize what sysdig prints to the screen. Another really nice benefit of the type system sysdig uses to encode fields is that they can all be used to customize the program output. Output customization happens with the –p command line flag, and works somewhat similarly to the C printf syntax. Here’s an example:
$ sysdig -p"user:%user.name dir:%evt.arg.path" evt.type=chdir
user:ubuntu dir:/root
user:ubuntu dir:/root/tmp
user:ubuntu dir:/root/Download
This one-liner filters on the chdir system calls (the ones that get called every time a user does a cd), and prints the user name and the directory where the user is going. Essentially, it lets you follow a user as she moves in the file system.
Some notes about the –p formatting syntax:
- Fields must be prepended with a %
- You can add arbitrary text in the string, exactly as you would do in the C printf.
- By default, a line is printed only if all the fields specified by –p are present in the event. You can, however, prepend the string with a * to make it print no matter what. In that case, the missing fields will be rendered as <NA>.
For example,
$ sysdig -p"%evt.type %evt.dir %evt.arg.name" evt.type=open
will only print exit open events, like this
open < /proc/1285/task/1399/stat
open < /proc/1285/task/1400/io
open < /proc/1285/task/1400/statm
because the enter events don’t contain the name argument, while
$ sysdig -p"*%evt.type %evt.dir %evt.arg.name" evt.type=open
will print both enter and exit open events, with a line finishing with <NA> for enter events:
open > <NA>
open < /proc/1285/task/1399/stat
open > <NA>
open < /proc/1285/task/1400/io
open > <NA>
open < /proc/1285/task/1400/statm
open > <NA>
Putting together filtering and output formatting makes sysdig a very flexible and powerful tool. Here are some examples:
$ sysdig -A -s 65000 -p"%evt.buffer" "proc.name=cat and evt.type=write and fd.num=1"
prints the standard output of a process (cat in this case). Note how we use the -A switch to render the result as a human readable string, and the –s switch to capture more than the usual 80 bytes of each write. Use -s with caution, it can generate huge capture files!
$ sysdig -p"%user.name) %proc.name %proc.args" evt.type=execve and evt.arg.ptid=bash
shows user, command name and arguments for every program launched by a real user (i.e. from bash).
$ sysdig -p"%user.name) %evt.arg.path" "evt.type=chdir"
shows the directories that interactive users visit
$ sysdig -p"user:%user.name process:%proc.name file:%fd.name" "evt.type=write and fd.name contains /etc/"
prints user, process, and file name for all the accesses to the /etc directory.
$ sysdig -p"%fd.name" "proc.name=apache and evt.type=accept"
lists TCP/IP endpoint information for all the connections received by apache. I can go on and on, but, well, you get the idea. :-) Are you interested in learning more useful sysdig one-liners? Visit the sysdig website or, even better, follow us on twitter. We’ll post new one-liners on a regular basis.
Sysdig’s chisels are little scripts that analyze the sysdig event stream to perform useful actions. Essentially, they enable you to do really cool stuff with your sysdig data. Just dig the data up, and then use a chisel to shape it into something beautiful. Get it? Awesome!
Chisels are written in Lua, a well known, powerful, and extremely efficient scripting language.
Go here for a full tutorial.