1 .\" Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
2 .\" Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
3 .\" Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
4 .\" Copyright (c) 1996-2017 The strace developers.
5 .\" All rights reserved.
7 .\" Redistribution and use in source and binary forms, with or without
8 .\" modification, are permitted provided that the following conditions
10 .\" 1. Redistributions of source code must retain the above copyright
11 .\" notice, this list of conditions and the following disclaimer.
12 .\" 2. Redistributions in binary form must reproduce the above copyright
13 .\" notice, this list of conditions and the following disclaimer in the
14 .\" documentation and/or other materials provided with the distribution.
15 .\" 3. The name of the author may not be used to endorse or promote products
16 .\" derived from this software without specific prior written permission.
18 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 .\" Like .OP, but with ellipsis at the end in order to signify that option
41 .\" can be provided multiple times. Based on .OP definition in groff's
45 . RI "[\fB\\$1\fP" "\ \\$2" "]...\&"
47 . RB "[" "\\$1" "]...\&"
52 . RI "\fB\\$1\fP" "\ \\$2"
56 .TH STRACE 1 "@MANPAGE_DATE@" "strace @VERSION@"
58 strace \- trace system calls and signals
61 .OP \-CdffhikqrtttTvVxxy
74 .OM \-E var\fR[=\fIval\fR]
76 .IR command " [" args ]
93 .OM \-E var\fR[=\fIval\fR]
95 .IR command " [" args ]
100 .IX "strace command" "" "\fLstrace\fR command"
107 It intercepts and records the system calls which are called
108 by a process and the signals which are received by a process.
109 The name of each system call, its arguments and its return value
110 are printed on standard error or to the file specified with the
115 is a useful diagnostic, instructional, and debugging tool.
116 System administrators, diagnosticians and trouble-shooters will find
117 it invaluable for solving problems with
118 programs for which the source is not readily available since
119 they do not need to be recompiled in order to trace them.
120 Students, hackers and the overly-curious will find that
121 a great deal can be learned about a system and its system calls by
122 tracing even ordinary programs. And programmers will find that
123 since system calls and signals are events that happen at the user/kernel
124 interface, a close examination of this boundary is very
125 useful for bug isolation, sanity checking and
126 attempting to capture race conditions.
128 Each line in the trace contains the system call name, followed
129 by its arguments in parentheses and its return value.
130 An example from stracing the command "cat /dev/null" is:
132 open("/dev/null", O_RDONLY) = 3
134 Errors (typically a return value of \-1) have the errno symbol
135 and error string appended.
137 open("/foo/bar", O_RDONLY) = \-1 ENOENT (No such file or directory)
139 Signals are printed as signal symbol and decoded siginfo structure.
140 An excerpt from stracing and interrupting the command "sleep 666" is:
142 sigsuspend([] <unfinished ...>
143 --- SIGINT {si_signo=SIGINT, si_code=SI_USER, si_pid=...} ---
144 +++ killed by SIGINT +++
146 If a system call is being executed and meanwhile another one is being called
147 from a different thread/process then
149 will try to preserve the order of those events and mark the ongoing call as
152 When the call returns it will be marked as
155 [pid 28772] select(4, [3], NULL, NULL, NULL <unfinished ...>
156 [pid 28779] clock_gettime(CLOCK_REALTIME, {1130322148, 939977000}) = 0
157 [pid 28772] <... select resumed> ) = 1 (in [3])
159 Interruption of a (restartable) system call by a signal delivery is processed
160 differently as kernel terminates the system call and also arranges its
161 immediate reexecution after the signal handler completes.
163 read(0, 0x7ffff72cf5cf, 1) = ? ERESTARTSYS (To be restarted)
165 rt_sigreturn(0xe) = 0
168 Arguments are printed in symbolic form with passion.
169 This example shows the shell performing ">>xyzzy" output redirection:
171 open("xyzzy", O_WRONLY|O_APPEND|O_CREAT, 0666) = 3
173 Here, the third argument of open is decoded by breaking down the
174 flag argument into its three bitwise-OR constituents and printing the
175 mode value in octal by tradition. Where the traditional or native
176 usage differs from ANSI or POSIX, the latter forms are preferred.
179 output is proven to be more readable than the source.
181 Structure pointers are dereferenced and the members are displayed
182 as appropriate. In most cases, arguments are formatted in the most C-like
184 For example, the essence of the command "ls \-l /dev/null" is captured as:
186 lstat("/dev/null", {st_mode=S_IFCHR|0666, st_rdev=makedev(1, 3), ...}) = 0
188 Notice how the 'struct stat' argument is dereferenced and how each member is
189 displayed symbolically. In particular, observe how the
191 member is carefully decoded into a bitwise-OR of symbolic and numeric values.
192 Also notice in this example that the first argument to
194 is an input to the system call and the second argument is an output.
195 Since output arguments are not modified if the system call fails, arguments may
196 not always be dereferenced. For example, retrying the "ls \-l" example
197 with a non-existent file produces the following line:
199 lstat("/foo/bar", 0xb004) = \-1 ENOENT (No such file or directory)
201 In this case the porch light is on but nobody is home.
205 are printed raw, with the unknown system call number printed in hexadecimal form
206 and prefixed with "syscall_":
208 syscall_0xbad(0xfedcba9876543210, 0xfedcba9876543211, 0xfedcba9876543212,
209 0xfedcba9876543213, 0xfedcba9876543214, 0xfedcba9876543215) = -1 (errno 38)
212 Character pointers are dereferenced and printed as C strings.
213 Non-printing characters in strings are normally represented by
214 ordinary C escape codes.
217 (32 by default) bytes of strings are printed;
218 longer strings have an ellipsis appended following the closing quote.
219 Here is a line from "ls \-l" where the
221 library routine is reading the password file:
223 read(3, "root::0:0:System Administrator:/"..., 1024) = 422
225 While structures are annotated using curly braces, simple pointers
226 and arrays are printed using square brackets with commas separating
227 elements. Here is an example from the command "id" on a system with
228 supplementary group ids:
230 getgroups(32, [100, 0]) = 2
232 On the other hand, bit-sets are also shown using square brackets
233 but set elements are separated only by a space. Here is the shell,
234 preparing to execute an external command:
236 sigprocmask(SIG_BLOCK, [CHLD TTOU], []) = 0
238 Here, the second argument is a bit-set of two signals,
239 .BR SIGCHLD " and " SIGTTOU .
240 In some cases, the bit-set is so full that printing out the unset
241 elements is more valuable. In that case, the bit-set is prefixed by
244 sigprocmask(SIG_UNBLOCK, ~[], NULL) = 0
246 Here, the second argument represents the full set of all signals.
251 Align return values in a specific column (default column 40).
254 Print the instruction pointer at the time of the system call.
257 Print the execution stack trace of the traced processes after each system call (experimental).
258 This option is available only if
260 is built with libunwind.
263 Write the trace output to the file
265 rather than to stderr.
270 If the argument begins with '|' or '!', the rest of the
271 argument is treated as a command and all output is piped to it.
272 This is convenient for piping the debugging output to a program
273 without affecting the redirections of executed programs.
274 The latter is not compatible with
279 Suppress messages about attaching, detaching etc. This happens
280 automatically when output is redirected to a file and the command
281 is run directly instead of attaching.
284 If given twice, suppress messages about process exit status.
287 Print a relative timestamp upon entry to each system call. This
288 records the time difference between the beginning of successive
292 Specify the maximum string size to print (the default is 32). Note
293 that filenames are not considered strings and are always printed in
297 Prefix each line of the trace with the wall clock time.
300 If given twice, the time printed will include the microseconds.
303 If given thrice, the time printed will include the microseconds
304 and the leading portion will be printed as the number
305 of seconds since the epoch.
308 Show the time spent in system calls. This records the time
309 difference between the beginning and the end of each system call.
312 Print all non-ASCII strings in hexadecimal string format.
315 Print all strings in hexadecimal string format.
318 Print paths associated with file descriptor arguments.
321 Print protocol specific information associated with socket file descriptors,
322 and block/character device number associated with device file descriptors.
326 Count time, calls, and errors for each system call and report a summary on
327 program exit, suppressing the regular output.
328 This attempts to show system time (CPU time spent running
329 in the kernel) independent of wall clock time. If
333 only aggregate totals for all traced processes are kept.
338 but also print regular output while processes are running.
341 Set the overhead for tracing system calls to
344 This is useful for overriding the default heuristic for guessing
345 how much time is spent in mere measuring when timing system calls using
348 option. The accuracy of the heuristic can be gauged by timing a given
349 program run without tracing (using
351 and comparing the accumulated
352 system call time to the total produced using
356 Sort the output of the histogram printed by the
358 option by the specified criterion. Legal values are
368 Summarise the time difference between the beginning and end of
369 each system call. The default is to summarise the system time.
373 A qualifying expression which modifies which events to trace
374 or how to trace them. The format of the expression is:
377 [\,\fIqualifier\/\fB=\fR][\fB!\fR][\fB?\fR]\,\fIvalue1\/\fR[\fB,\fR[\fB?\fR]\,\fIvalue2\/\fR]...
395 is a qualifier-dependent symbol or number. The default
398 Using an exclamation mark negates the set of values. For example,
401 .BR \-e "\ " trace = open
402 which in turn means trace only the
404 system call. By contrast,
405 .BR \-e "\ " trace "=!" open
406 means to trace every system call except
408 Question mark before the syscall qualification allows suppression of error
409 in case no syscalls matched the qualification provided.
410 In addition, the special values
414 have the obvious meanings.
416 Note that some shells use the exclamation point for history
417 expansion even inside quoted arguments. If so, you must escape
418 the exclamation point with a backslash.
420 \fB\-e\ trace\fR=\,\fIset\fR
421 Trace only the specified set of system calls. The
423 option is useful for determining which system calls might be useful
424 to trace. For example,
425 .BR trace = open,close,read,write
427 trace those four system calls. Be careful when making inferences
428 about the user/kernel boundary if only a subset of system calls
429 are being monitored. The default is
432 \fB\-e\ trace\fR=/\,\fIregex\fR
433 Trace only those system calls that match the
437 Extended Regular Expression syntax (see
440 .BR "\-e\ trace" = %file
442 .BR "\-e\ trace" = file " (deprecated)"
443 Trace all system calls which take a file name as an argument. You
444 can think of this as an abbreviation for
445 .BR "\-e\ trace" = open , stat , chmod , unlink ,...
446 which is useful to seeing what files the process is referencing.
447 Furthermore, using the abbreviation will ensure that you don't
448 accidentally forget to include a call like
450 in the list. Betchya woulda forgot that one.
452 .BR "\-e\ trace" = %process
454 .BR "\-e\ trace" = process " (deprecated)"
455 Trace all system calls which involve process management. This
456 is useful for watching the fork, wait, and exec steps of a process.
458 .BR "\-e\ trace" = %network
460 .BR "\-e\ trace" = network " (deprecated)"
461 Trace all the network related system calls.
463 .BR "\-e\ trace" = %signal
465 .BR "\-e\ trace" = signal " (deprecated)"
466 Trace all signal related system calls.
468 .BR "\-e\ trace" = %ipc
470 .BR "\-e\ trace" = ipc " (deprecated)"
471 Trace all IPC related system calls.
473 .BR "\-e\ trace" = %desc
475 .BR "\-e\ trace" = desc " (deprecated)"
476 Trace all file descriptor related system calls.
478 .BR "\-e\ trace" = %memory
480 .BR "\-e\ trace" = memory " (deprecated)"
481 Trace all memory mapping related system calls.
483 .BR "\-e\ trace" = %stat
484 Trace stat syscall variants.
486 .BR "\-e\ trace" = %lstat
487 Trace lstat syscall variants.
489 .BR "\-e\ trace" = %fstat
490 Trace fstat and fstatat syscall variants.
492 .BR "\-e\ trace" = %%stat
493 Trace syscalls used for requesting file status (stat, lstat, fstat, fstatat,
494 statx, and their variants).
496 .BR "\-e\ trace" = %statfs
497 Trace statfs, statfs64, statvfs, osf_statfs, and osf_statfs64 system calls.
498 The same effect can be achieved with
499 .BR "\-e\ trace" = /^(.*_)?statv?fs
502 .BR "\-e\ trace" = %fstatfs
503 Trace fstatfs, fstatfs64, fstatvfs, osf_fstatfs, and osf_fstatfs64 system calls.
504 The same effect can be achieved with
505 .BR "\-e\ trace" = /fstatv?fs
508 .BR "\-e\ trace" = %%statfs
509 Trace syscalls related to file system statistics (statfs-like, fstatfs-like,
510 and ustat). The same effect can be achieved with
511 .BR "\-e\ trace" = /statv?fs|fsstat|ustat
514 .BR "\-e\ trace" = %pure
515 Trace syscalls that always succeed and have no arguments.
516 Currently, this list includes
517 .BR arc_gettls "(2), " getdtablesize "(2), " getegid "(2), " getegid32 "(2),"
518 .BR geteuid "(2), " geteuid32 "(2), " getgid "(2), " getgid32 "(2),"
519 .BR getpagesize "(2), " getpgrp "(2), " getpid "(2), " getppid "(2),"
520 .BR get_thread_area (2)
521 (on architectures other than x86),
522 .BR gettid "(2), " get_tls "(2), " getuid "(2), " getuid32 "(2),"
523 .BR getxgid "(2), " getxpid "(2), " getxuid "(2), " kern_features "(2), and"
524 .BR metag_get_tls "(2)"
527 \fB\-e\ abbrev\fR=\,\fIset\fR
528 Abbreviate the output from printing each member of large structures.
533 option has the effect of
536 \fB\-e\ verbose\fR=\,\fIset\fR
537 Dereference structures for the specified set of system calls. The
541 \fB\-e\ raw\fR=\,\fIset\fR
542 Print raw, undecoded arguments for the specified set of system calls.
543 This option has the effect of causing all arguments to be printed
544 in hexadecimal. This is mostly useful if you don't trust the
545 decoding or you need to know the actual numeric value of an
548 \fB\-e\ signal\fR=\,\fIset\fR
549 Trace only the specified subset of signals. The default is
552 .BR signal "=!" SIGIO
557 signals not to be traced.
559 \fB\-e\ read\fR=\,\fIset\fR
560 Perform a full hexadecimal and ASCII dump of all the data read from
561 file descriptors listed in the specified set. For example, to see
562 all input activity on file descriptors
567 \fB\-e\ read\fR=\,\fI3\fR,\fI5\fR.
568 Note that this is independent from the normal tracing of the
570 system call which is controlled by the option
571 .BR -e "\ " trace = read .
573 \fB\-e\ write\fR=\,\fIset\fR
574 Perform a full hexadecimal and ASCII dump of all the data written to
575 file descriptors listed in the specified set. For example, to see
576 all output activity on file descriptors
581 \fB\-e\ write\fR=\,\fI3\fR,\,\fI5\fR.
582 Note that this is independent from the normal tracing of the
584 system call which is controlled by the option
585 .BR -e "\ " trace = write .
587 \fB\-e\ inject\fR=\,\fIset\/\fR[:\fBerror\fR=\,\fIerrno\/\fR|:\fBretval\fR=\,\fIvalue\/\fR][:\fBsignal\fR=\,\fIsig\/\fR][:\fBdelay_enter\fR=\,\fIusecs\/\fR][:\fBdelay_exit\fR=\,\fIusecs\/\fR][:\fBwhen\fR=\,\fIexpr\/\fR]
588 Perform syscall tampering for the specified set of syscalls.
597 options has to be specified.
601 are mutually exclusive.
603 If :\fBerror\fR=\,\fIerrno\/\fR option is specified,
604 a fault is injected into a syscall invocation:
605 the syscall number is replaced by -1 which corresponds to an invalid syscall,
606 and the error code is specified using a symbolic
610 or a numeric value within 1..4095 range.
612 If :\fBretval\fR=\,\fIvalue\/\fR option is specified,
613 success injection is performed: the syscall number is replaced by -1,
614 but a bogus success value is returned to the callee.
616 If :\fBsignal\fR=\,\fIsig\/\fR option is specified with either a symbolic value
619 or a numeric value within 1..\fBSIGRTMAX\fR range,
620 that signal is delivered on entering every syscall specified by the
623 If :\fBdelay_enter\fR=\,\fIusecs\/\fR or :\fBdelay_exit\fR=\,\fIusecs\/\fR
624 options are specified, delay injection is performed: the tracee is delayed
627 microseconds on entering or exiting the syscall.
629 If :\fBsignal\fR=\,\fIsig\/\fR option is specified without
630 :\fBerror\fR=\,\fIerrno\/\fR, :\fBretval\fR=\,\fIvalue\/\fR or
631 :\fBdelay_{enter,exit}\fR=\,\fIusecs\/\fR options,
634 is delivered without a syscall fault or delay injection.
635 Conversely, :\fBerror\fR=\,\fIerrno\/\fR or
636 :\fBretval\fR=\,\fIvalue\/\fR option without
637 :\fBdelay_enter\fR=\,\fIusecs\/\fR,
638 :\fBdelay_exit\fR=\,\fIusecs\/\fR or
639 :\fBsignal\fR=\,\fIsig\/\fR options injects a fault without delivering a signal
640 or injecting a delay, etc.
642 If both :\fBerror\fR=\,\fIerrno\/\fR or :\fBretval\fR=\,\fIvalue\/\fR
643 and :\fBsignal\fR=\,\fIsig\/\fR options are specified, then both
644 a fault or success is injected and a signal is delivered.
646 Unless a :\fBwhen\fR=\,\fIexpr\fR subexpression is specified,
647 an injection is being made into every invocation of each syscall from the
650 The format of the subexpression is one of the following:
655 For every syscall from the
657 perform an injection for the syscall invocation number
664 For every syscall from the
666 perform injections for the syscall invocation number
668 and all subsequent invocations.
671 \fIfirst\/\fB+\fIstep\fR
673 For every syscall from the
675 perform injections for syscall invocations number
678 .IR first + step + step ,
683 For example, to fail each third and subsequent chdir syscalls with
686 \fB\-e\ inject\fR=\,\fIchdir\/\fR:\fBerror\fR=\,\fIENOENT\/\fR:\fBwhen\fR=\,\fI3\/\fB+\fR.
688 The valid range for numbers
694 An injection expression can contain only one
698 specification, and only one
700 specification. If an injection expression contains multiple
702 specifications, the last one takes precedence.
704 Accounting of syscalls that are subject to injection
705 is done per syscall and per tracee.
707 Specification of syscall injection can be combined
708 with other syscall filtering options, for example,
709 \fB\-P \fI/dev/urandom \fB\-e inject\fR=\,\fIfile\/\fR:\fBerror\fR=\,\fIENOENT\fR.
712 \fB\-e\ fault\fR=\,\fIset\/\fR[:\fBerror\fR=\,\fIerrno\/\fR][:\fBwhen\fR=\,\fIexpr\/\fR]
713 Perform syscall fault injection for the specified set of syscalls.
715 This is equivalent to more generic
716 \fB\-e\ inject\fR= expression with default value of
723 Trace only system calls accessing
727 options can be used to specify several paths.
730 Print unabbreviated versions of environment, stat, termios, etc.
731 calls. These structures are very common in calls and so the default
732 behavior displays a reasonable subset of structure members. Use
733 this option to get all of the gory details.
737 If specified syscall is reached, detach from traced process.
740 syscall is supported. This option is useful if you want to trace
741 multi-threaded process and therefore require -f, but don't want
742 to trace its (potentially very complex) children.
745 Run tracer process as a detached grandchild, not as parent of the
746 tracee. This reduces the visible effect of
748 by keeping the tracee a direct child of the calling process.
751 Trace child processes as they are created by currently traced
752 processes as a result of the
757 system calls. Note that
761 will attach all threads of process PID if it is multi-threaded,
762 not only thread with thread_id = PID.
768 option is in effect, each processes trace is written to
770 where pid is the numeric process id of each process.
771 This is incompatible with
773 since no per-process counts are kept.
775 One might want to consider using
776 .BR strace-log-merge (1)
777 to obtain a combined strace log view.
779 .BI "\-I " interruptible
780 When strace can be interrupted by signals (such as pressing ^C).
781 1: no signals are blocked; 2: fatal signals are blocked while decoding syscall
782 (default); 3: fatal signals are always blocked (default if '-o FILE PROG');
783 4: fatal signals and SIGTSTP (^Z) are always blocked (useful to make
784 strace -o FILE PROG not stop on ^Z).
787 \fB\-E\ \fIvar\fR=\,\fIval\fR
790 in its list of environment variables.
795 from the inherited list of environment variables before passing it on to
799 Attach to the process with the process
803 The trace may be terminated
804 at any time by a keyboard interrupt signal (\c
807 will respond by detaching itself from the traced process(es)
808 leaving it (them) to continue running.
811 options can be used to attach to many processes in addition to
813 (which is optional if at least one
817 "`pidof PROG`" syntax is supported.
820 Run command with the user \s-1ID\s0, group \s-2ID\s0, and
821 supplementary groups of
823 This option is only useful when running as root and enables the
824 correct execution of setuid and/or setgid binaries.
825 Unless this option is used setuid and setgid programs are executed
826 without effective privileges.
830 Show some debugging output of
832 itself on the standard error.
835 This option is deprecated. It is retained for backward compatibility only
836 and may be removed in future releases.
837 Usage of multiple instances of
839 option is still equivalent to a single
841 and it is ignored at all if used along with one or more instances of
846 Print the help summary.
849 Print the version number of
856 exits with the same exit status.
859 is terminated by a signal,
861 terminates itself with the same signal, so that
863 can be used as a wrapper process transparent to the invoking parent process.
864 Note that parent-child relationship (signal stop notifications,
865 getppid() value, etc) between traced process and its parent are not preserved
876 is zero unless no processes has been attached or there was an unexpected error
877 in doing the tracing.
878 .SH "SETUID INSTALLATION"
881 is installed setuid to root then the invoking user will be able to
882 attach to and trace processes owned by any user.
883 In addition setuid and setgid programs will be executed and traced
884 with the correct effective privileges.
885 Since only users trusted with full root privileges should be allowed
887 it only makes sense to install
889 as setuid to root when the users who can execute it are restricted
890 to those users who have this trust.
891 For example, it makes sense to install a special version of
893 with mode 'rwsr-xr--', user
899 group are trusted users.
900 If you do use this feature, please remember to install
901 a regular non-setuid version of
903 for ordinary users to use.
904 .SH "MULTIPLE PERSONALITY SUPPORT"
905 On some architectures,
907 supports decoding of syscalls for processes that use different ABI rather than
911 Specifically, in addition to decoding native ABI,
913 can decode the following ABIs on the following architectures:
918 Architecture ABIs supported
919 x86_64 i386, x32 (when built as an x86_64 application); i386 (when built as an x32 application)
920 AArch64 ARM 32-bit EABI
921 PowerPC 64-bit PowerPC 32-bit
922 RISC-V 64-bit RISC-V 32-bit
924 SPARC 64-bit SPARC 32-bit
925 TILE 64-bit TILE 32-bit
928 This support is optional and relies on ability to generate and parse structure
929 definitions during the build time.
930 Please refer to the output of the
932 command in order to figure out what support is available in your strace build
933 ("non-native" refers to an ABI that differs from the ABI strace has):
937 can trace and properly decode non-native 32-bit binaries.
941 can trace, but cannot properly decode non-native 32-bit binaries.
945 can trace and properly decode non-native 32-on-64-bit binaries.
949 can trace, but cannot properly decode non-native 32-on-64-bit binaries.
951 If the output contains neither
955 then decoding of non-native 32-bit binaries is not implemented at all
958 Likewise, if the output contains neither
962 then decoding of non-native 32-on-64-bit binaries is not implemented at all
965 It is a pity that so much tracing clutter is produced by systems
966 employing shared libraries.
968 It is instructive to think about system call inputs and outputs
969 as data-flow across the user/kernel boundary. Because user-space
970 and kernel-space are separate and address-protected, it is
971 sometimes possible to make deductive inferences about process
972 behavior using inputs and outputs as propositions.
974 In some cases, a system call will differ from the documented behavior
975 or have a different name. For example, the
977 system call does not have
981 library function uses
983 system call on modern (2.6.38+) kernels. These
984 discrepancies are normal but idiosyncratic characteristics of the
985 system call interface and are accounted for by C library wrapper
988 Some system calls have different names in different architectures and
989 personalities. In these cases, system call filtering and printing
990 uses the names that match corresponding
992 kernel macros of the tracee's architecture and personality.
993 There are two exceptions from this general rule:
994 .BR arm_fadvise64_64 (2)
996 .BR xtensa_fadvise64_64 (2)
997 Xtensa syscall are filtered and printed as
998 .BR fadvise64_64 (2).
1000 On some platforms a process that is attached to with the
1002 option may observe a spurious EINTR return from the current
1003 system call that is not restartable. (Ideally, all system calls
1004 should be restarted on strace attach, making the attach invisible
1005 to the traced process, but a few system calls aren't.
1006 Arguably, every instance of such behavior is a kernel bug.)
1007 This may have an unpredictable effect on the process
1008 if the process takes no action to restart the system call.
1012 executes the specified
1014 directly and does not employ a shell for that, scripts without shebang
1015 that usually run just fine when invoked by shell fail to execute with
1018 It is advisable to manually supply a shell as a
1020 with the script as its argument.
1022 Programs that use the
1027 privileges while being traced.
1029 A traced process runs slowly.
1031 Traced processes which are descended from
1033 may be left running after an interrupt signal (\c
1038 was written by Paul Kranenburg
1039 for SunOS and was inspired by its
1042 The SunOS version of
1044 was ported to Linux and enhanced
1045 by Branko Lankester, who also wrote the Linux kernel support.
1046 Even though Paul released
1049 Branko's work was based on Paul's
1051 1.5 release from 1991.
1052 In 1993, Rick Sladkey merged
1054 2.5 for SunOS and the second release of
1056 for Linux, added many of the features of
1058 from SVR4, and produced an
1060 that worked on both platforms. In 1994 Rick ported
1062 to SVR4 and Solaris and wrote the
1063 automatic configuration support. In 1995 he ported
1066 and tired of writing about himself in the third person.
1068 Beginning with 1996,
1070 was maintained by Wichert Akkerman.
1073 development migrated to CVS; ports to FreeBSD and many architectures on Linux
1074 (including ARM, IA-64, MIPS, PA-RISC, PowerPC, s390, SPARC) were introduced.
1075 In 2002, the burden of
1077 maintainership was transferred to Ronald McGrath.
1080 gained support for several new Linux architectures (AMD64, s390x, SuperH),
1081 bi-architecture support for some of them, and received numerous additions and
1082 improvements in syscalls decoders on Linux;
1084 development migrated to
1089 is actively maintained by Dmitry Levin.
1091 gained support for AArch64, ARC, AVR32, Blackfin, Meta, Nios II, OpenSISC 1000,
1092 RISC-V, Tile/TileGx, Xtensa architectures since that time.
1093 In 2012, unmaintained and apparently broken support for non-Linux operating
1094 systems was removed.
1097 gained support for path tracing and file descriptor path decoding.
1098 In 2014, support for stack traces printing was added.
1099 In 2016, syscall fault injection was implemented.
1101 For the additional information, please refer to the
1105 repository commit log.
1109 should be reported to the
1111 mailing list at <strace\-devel@lists.strace.io>.
1113 .BR strace-log-merge (1),