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 option uses the monotonic clock time for measuring time difference and not the
293 wall clock time, its measurements can differ from the difference in time
299 Specify the maximum string size to print (the default is 32). Note
300 that filenames are not considered strings and are always printed in
304 Prefix each line of the trace with the wall clock time.
307 If given twice, the time printed will include the microseconds.
310 If given thrice, the time printed will include the microseconds
311 and the leading portion will be printed as the number
312 of seconds since the epoch.
315 Show the time spent in system calls. This records the time
316 difference between the beginning and the end of each system call.
319 Print all non-ASCII strings in hexadecimal string format.
322 Print all strings in hexadecimal string format.
325 Print paths associated with file descriptor arguments.
328 Print protocol specific information associated with socket file descriptors,
329 and block/character device number associated with device file descriptors.
333 Count time, calls, and errors for each system call and report a summary on
334 program exit, suppressing the regular output.
335 This attempts to show system time (CPU time spent running
336 in the kernel) independent of wall clock time. If
340 only aggregate totals for all traced processes are kept.
345 but also print regular output while processes are running.
348 Set the overhead for tracing system calls to
351 This is useful for overriding the default heuristic for guessing
352 how much time is spent in mere measuring when timing system calls using
355 option. The accuracy of the heuristic can be gauged by timing a given
356 program run without tracing (using
358 and comparing the accumulated
359 system call time to the total produced using
363 Sort the output of the histogram printed by the
365 option by the specified criterion. Legal values are
375 Summarise the time difference between the beginning and end of
376 each system call. The default is to summarise the system time.
380 A qualifying expression which modifies which events to trace
381 or how to trace them. The format of the expression is:
384 [\,\fIqualifier\/\fB=\fR][\fB!\fR][\fB?\fR]\,\fIvalue1\/\fR[\fB,\fR[\fB?\fR]\,\fIvalue2\/\fR]...
402 is a qualifier-dependent symbol or number. The default
405 Using an exclamation mark negates the set of values. For example,
408 .BR \-e "\ " trace = open
409 which in turn means trace only the
411 system call. By contrast,
412 .BR \-e "\ " trace "=!" open
413 means to trace every system call except
415 Question mark before the syscall qualification allows suppression of error
416 in case no syscalls matched the qualification provided.
417 In addition, the special values
421 have the obvious meanings.
423 Note that some shells use the exclamation point for history
424 expansion even inside quoted arguments. If so, you must escape
425 the exclamation point with a backslash.
427 \fB\-e\ trace\fR=\,\fIset\fR
428 Trace only the specified set of system calls. The
430 option is useful for determining which system calls might be useful
431 to trace. For example,
432 .BR trace = open,close,read,write
434 trace those four system calls. Be careful when making inferences
435 about the user/kernel boundary if only a subset of system calls
436 are being monitored. The default is
439 \fB\-e\ trace\fR=/\,\fIregex\fR
440 Trace only those system calls that match the
444 Extended Regular Expression syntax (see
447 .BR "\-e\ trace" = %file
449 .BR "\-e\ trace" = file " (deprecated)"
450 Trace all system calls which take a file name as an argument. You
451 can think of this as an abbreviation for
452 .BR "\-e\ trace" = open , stat , chmod , unlink ,...
453 which is useful to seeing what files the process is referencing.
454 Furthermore, using the abbreviation will ensure that you don't
455 accidentally forget to include a call like
457 in the list. Betchya woulda forgot that one.
459 .BR "\-e\ trace" = %process
461 .BR "\-e\ trace" = process " (deprecated)"
462 Trace all system calls which involve process management. This
463 is useful for watching the fork, wait, and exec steps of a process.
465 .BR "\-e\ trace" = %network
467 .BR "\-e\ trace" = network " (deprecated)"
468 Trace all the network related system calls.
470 .BR "\-e\ trace" = %signal
472 .BR "\-e\ trace" = signal " (deprecated)"
473 Trace all signal related system calls.
475 .BR "\-e\ trace" = %ipc
477 .BR "\-e\ trace" = ipc " (deprecated)"
478 Trace all IPC related system calls.
480 .BR "\-e\ trace" = %desc
482 .BR "\-e\ trace" = desc " (deprecated)"
483 Trace all file descriptor related system calls.
485 .BR "\-e\ trace" = %memory
487 .BR "\-e\ trace" = memory " (deprecated)"
488 Trace all memory mapping related system calls.
490 .BR "\-e\ trace" = %stat
491 Trace stat syscall variants.
493 .BR "\-e\ trace" = %lstat
494 Trace lstat syscall variants.
496 .BR "\-e\ trace" = %fstat
497 Trace fstat and fstatat syscall variants.
499 .BR "\-e\ trace" = %%stat
500 Trace syscalls used for requesting file status (stat, lstat, fstat, fstatat,
501 statx, and their variants).
503 .BR "\-e\ trace" = %statfs
504 Trace statfs, statfs64, statvfs, osf_statfs, and osf_statfs64 system calls.
505 The same effect can be achieved with
506 .BR "\-e\ trace" = /^(.*_)?statv?fs
509 .BR "\-e\ trace" = %fstatfs
510 Trace fstatfs, fstatfs64, fstatvfs, osf_fstatfs, and osf_fstatfs64 system calls.
511 The same effect can be achieved with
512 .BR "\-e\ trace" = /fstatv?fs
515 .BR "\-e\ trace" = %%statfs
516 Trace syscalls related to file system statistics (statfs-like, fstatfs-like,
517 and ustat). The same effect can be achieved with
518 .BR "\-e\ trace" = /statv?fs|fsstat|ustat
521 .BR "\-e\ trace" = %pure
522 Trace syscalls that always succeed and have no arguments.
523 Currently, this list includes
524 .BR arc_gettls "(2), " getdtablesize "(2), " getegid "(2), " getegid32 "(2),"
525 .BR geteuid "(2), " geteuid32 "(2), " getgid "(2), " getgid32 "(2),"
526 .BR getpagesize "(2), " getpgrp "(2), " getpid "(2), " getppid "(2),"
527 .BR get_thread_area (2)
528 (on architectures other than x86),
529 .BR gettid "(2), " get_tls "(2), " getuid "(2), " getuid32 "(2),"
530 .BR getxgid "(2), " getxpid "(2), " getxuid "(2), " kern_features "(2), and"
531 .BR metag_get_tls "(2)"
534 \fB\-e\ abbrev\fR=\,\fIset\fR
535 Abbreviate the output from printing each member of large structures.
540 option has the effect of
543 \fB\-e\ verbose\fR=\,\fIset\fR
544 Dereference structures for the specified set of system calls. The
548 \fB\-e\ raw\fR=\,\fIset\fR
549 Print raw, undecoded arguments for the specified set of system calls.
550 This option has the effect of causing all arguments to be printed
551 in hexadecimal. This is mostly useful if you don't trust the
552 decoding or you need to know the actual numeric value of an
555 \fB\-e\ signal\fR=\,\fIset\fR
556 Trace only the specified subset of signals. The default is
559 .BR signal "=!" SIGIO
564 signals not to be traced.
566 \fB\-e\ read\fR=\,\fIset\fR
567 Perform a full hexadecimal and ASCII dump of all the data read from
568 file descriptors listed in the specified set. For example, to see
569 all input activity on file descriptors
574 \fB\-e\ read\fR=\,\fI3\fR,\fI5\fR.
575 Note that this is independent from the normal tracing of the
577 system call which is controlled by the option
578 .BR -e "\ " trace = read .
580 \fB\-e\ write\fR=\,\fIset\fR
581 Perform a full hexadecimal and ASCII dump of all the data written to
582 file descriptors listed in the specified set. For example, to see
583 all output activity on file descriptors
588 \fB\-e\ write\fR=\,\fI3\fR,\,\fI5\fR.
589 Note that this is independent from the normal tracing of the
591 system call which is controlled by the option
592 .BR -e "\ " trace = write .
594 \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]
595 Perform syscall tampering for the specified set of syscalls.
604 options has to be specified.
608 are mutually exclusive.
610 If :\fBerror\fR=\,\fIerrno\/\fR option is specified,
611 a fault is injected into a syscall invocation:
612 the syscall number is replaced by -1 which corresponds to an invalid syscall,
613 and the error code is specified using a symbolic
617 or a numeric value within 1..4095 range.
619 If :\fBretval\fR=\,\fIvalue\/\fR option is specified,
620 success injection is performed: the syscall number is replaced by -1,
621 but a bogus success value is returned to the callee.
623 If :\fBsignal\fR=\,\fIsig\/\fR option is specified with either a symbolic value
626 or a numeric value within 1..\fBSIGRTMAX\fR range,
627 that signal is delivered on entering every syscall specified by the
630 If :\fBdelay_enter\fR=\,\fIusecs\/\fR or :\fBdelay_exit\fR=\,\fIusecs\/\fR
631 options are specified, delay injection is performed: the tracee is delayed
634 microseconds on entering or exiting the syscall.
636 If :\fBsignal\fR=\,\fIsig\/\fR option is specified without
637 :\fBerror\fR=\,\fIerrno\/\fR, :\fBretval\fR=\,\fIvalue\/\fR or
638 :\fBdelay_{enter,exit}\fR=\,\fIusecs\/\fR options,
641 is delivered without a syscall fault or delay injection.
642 Conversely, :\fBerror\fR=\,\fIerrno\/\fR or
643 :\fBretval\fR=\,\fIvalue\/\fR option without
644 :\fBdelay_enter\fR=\,\fIusecs\/\fR,
645 :\fBdelay_exit\fR=\,\fIusecs\/\fR or
646 :\fBsignal\fR=\,\fIsig\/\fR options injects a fault without delivering a signal
647 or injecting a delay, etc.
649 If both :\fBerror\fR=\,\fIerrno\/\fR or :\fBretval\fR=\,\fIvalue\/\fR
650 and :\fBsignal\fR=\,\fIsig\/\fR options are specified, then both
651 a fault or success is injected and a signal is delivered.
653 Unless a :\fBwhen\fR=\,\fIexpr\fR subexpression is specified,
654 an injection is being made into every invocation of each syscall from the
657 The format of the subexpression is one of the following:
662 For every syscall from the
664 perform an injection for the syscall invocation number
671 For every syscall from the
673 perform injections for the syscall invocation number
675 and all subsequent invocations.
678 \fIfirst\/\fB+\fIstep\fR
680 For every syscall from the
682 perform injections for syscall invocations number
685 .IR first + step + step ,
690 For example, to fail each third and subsequent chdir syscalls with
693 \fB\-e\ inject\fR=\,\fIchdir\/\fR:\fBerror\fR=\,\fIENOENT\/\fR:\fBwhen\fR=\,\fI3\/\fB+\fR.
695 The valid range for numbers
701 An injection expression can contain only one
705 specification, and only one
707 specification. If an injection expression contains multiple
709 specifications, the last one takes precedence.
711 Accounting of syscalls that are subject to injection
712 is done per syscall and per tracee.
714 Specification of syscall injection can be combined
715 with other syscall filtering options, for example,
716 \fB\-P \fI/dev/urandom \fB\-e inject\fR=\,\fIfile\/\fR:\fBerror\fR=\,\fIENOENT\fR.
719 \fB\-e\ fault\fR=\,\fIset\/\fR[:\fBerror\fR=\,\fIerrno\/\fR][:\fBwhen\fR=\,\fIexpr\/\fR]
720 Perform syscall fault injection for the specified set of syscalls.
722 This is equivalent to more generic
723 \fB\-e\ inject\fR= expression with default value of
730 Trace only system calls accessing
734 options can be used to specify several paths.
737 Print unabbreviated versions of environment, stat, termios, etc.
738 calls. These structures are very common in calls and so the default
739 behavior displays a reasonable subset of structure members. Use
740 this option to get all of the gory details.
744 If specified syscall is reached, detach from traced process.
747 syscall is supported. This option is useful if you want to trace
748 multi-threaded process and therefore require -f, but don't want
749 to trace its (potentially very complex) children.
752 Run tracer process as a detached grandchild, not as parent of the
753 tracee. This reduces the visible effect of
755 by keeping the tracee a direct child of the calling process.
758 Trace child processes as they are created by currently traced
759 processes as a result of the
764 system calls. Note that
768 will attach all threads of process PID if it is multi-threaded,
769 not only thread with thread_id = PID.
775 option is in effect, each processes trace is written to
777 where pid is the numeric process id of each process.
778 This is incompatible with
780 since no per-process counts are kept.
782 One might want to consider using
783 .BR strace-log-merge (1)
784 to obtain a combined strace log view.
786 .BI "\-I " interruptible
787 When strace can be interrupted by signals (such as pressing ^C).
788 1: no signals are blocked; 2: fatal signals are blocked while decoding syscall
789 (default); 3: fatal signals are always blocked (default if '-o FILE PROG');
790 4: fatal signals and SIGTSTP (^Z) are always blocked (useful to make
791 strace -o FILE PROG not stop on ^Z).
794 \fB\-E\ \fIvar\fR=\,\fIval\fR
797 in its list of environment variables.
802 from the inherited list of environment variables before passing it on to
806 Attach to the process with the process
810 The trace may be terminated
811 at any time by a keyboard interrupt signal (\c
814 will respond by detaching itself from the traced process(es)
815 leaving it (them) to continue running.
818 options can be used to attach to many processes in addition to
820 (which is optional if at least one
824 "`pidof PROG`" syntax is supported.
827 Run command with the user \s-1ID\s0, group \s-2ID\s0, and
828 supplementary groups of
830 This option is only useful when running as root and enables the
831 correct execution of setuid and/or setgid binaries.
832 Unless this option is used setuid and setgid programs are executed
833 without effective privileges.
837 Show some debugging output of
839 itself on the standard error.
842 This option is deprecated. It is retained for backward compatibility only
843 and may be removed in future releases.
844 Usage of multiple instances of
846 option is still equivalent to a single
848 and it is ignored at all if used along with one or more instances of
853 Print the help summary.
856 Print the version number of
863 exits with the same exit status.
866 is terminated by a signal,
868 terminates itself with the same signal, so that
870 can be used as a wrapper process transparent to the invoking parent process.
871 Note that parent-child relationship (signal stop notifications,
872 getppid() value, etc) between traced process and its parent are not preserved
883 is zero unless no processes has been attached or there was an unexpected error
884 in doing the tracing.
885 .SH "SETUID INSTALLATION"
888 is installed setuid to root then the invoking user will be able to
889 attach to and trace processes owned by any user.
890 In addition setuid and setgid programs will be executed and traced
891 with the correct effective privileges.
892 Since only users trusted with full root privileges should be allowed
894 it only makes sense to install
896 as setuid to root when the users who can execute it are restricted
897 to those users who have this trust.
898 For example, it makes sense to install a special version of
900 with mode 'rwsr-xr--', user
906 group are trusted users.
907 If you do use this feature, please remember to install
908 a regular non-setuid version of
910 for ordinary users to use.
911 .SH "MULTIPLE PERSONALITY SUPPORT"
912 On some architectures,
914 supports decoding of syscalls for processes that use different ABI rather than
918 Specifically, in addition to decoding native ABI,
920 can decode the following ABIs on the following architectures:
925 Architecture ABIs supported
926 x86_64 i386, x32 (when built as an x86_64 application); i386 (when built as an x32 application)
927 AArch64 ARM 32-bit EABI
928 PowerPC 64-bit PowerPC 32-bit
929 RISC-V 64-bit RISC-V 32-bit
931 SPARC 64-bit SPARC 32-bit
932 TILE 64-bit TILE 32-bit
935 This support is optional and relies on ability to generate and parse structure
936 definitions during the build time.
937 Please refer to the output of the
939 command in order to figure out what support is available in your strace build
940 ("non-native" refers to an ABI that differs from the ABI strace has):
944 can trace and properly decode non-native 32-bit binaries.
948 can trace, but cannot properly decode non-native 32-bit binaries.
952 can trace and properly decode non-native 32-on-64-bit binaries.
956 can trace, but cannot properly decode non-native 32-on-64-bit binaries.
958 If the output contains neither
962 then decoding of non-native 32-bit binaries is not implemented at all
965 Likewise, if the output contains neither
969 then decoding of non-native 32-on-64-bit binaries is not implemented at all
972 It is a pity that so much tracing clutter is produced by systems
973 employing shared libraries.
975 It is instructive to think about system call inputs and outputs
976 as data-flow across the user/kernel boundary. Because user-space
977 and kernel-space are separate and address-protected, it is
978 sometimes possible to make deductive inferences about process
979 behavior using inputs and outputs as propositions.
981 In some cases, a system call will differ from the documented behavior
982 or have a different name. For example, the
984 system call does not have
988 library function uses
990 system call on modern (2.6.38+) kernels. These
991 discrepancies are normal but idiosyncratic characteristics of the
992 system call interface and are accounted for by C library wrapper
995 Some system calls have different names in different architectures and
996 personalities. In these cases, system call filtering and printing
997 uses the names that match corresponding
999 kernel macros of the tracee's architecture and personality.
1000 There are two exceptions from this general rule:
1001 .BR arm_fadvise64_64 (2)
1003 .BR xtensa_fadvise64_64 (2)
1004 Xtensa syscall are filtered and printed as
1005 .BR fadvise64_64 (2).
1007 On some platforms a process that is attached to with the
1009 option may observe a spurious EINTR return from the current
1010 system call that is not restartable. (Ideally, all system calls
1011 should be restarted on strace attach, making the attach invisible
1012 to the traced process, but a few system calls aren't.
1013 Arguably, every instance of such behavior is a kernel bug.)
1014 This may have an unpredictable effect on the process
1015 if the process takes no action to restart the system call.
1019 executes the specified
1021 directly and does not employ a shell for that, scripts without shebang
1022 that usually run just fine when invoked by shell fail to execute with
1025 It is advisable to manually supply a shell as a
1027 with the script as its argument.
1029 Programs that use the
1034 privileges while being traced.
1036 A traced process runs slowly.
1038 Traced processes which are descended from
1040 may be left running after an interrupt signal (\c
1045 was written by Paul Kranenburg
1046 for SunOS and was inspired by its
1049 The SunOS version of
1051 was ported to Linux and enhanced
1052 by Branko Lankester, who also wrote the Linux kernel support.
1053 Even though Paul released
1056 Branko's work was based on Paul's
1058 1.5 release from 1991.
1059 In 1993, Rick Sladkey merged
1061 2.5 for SunOS and the second release of
1063 for Linux, added many of the features of
1065 from SVR4, and produced an
1067 that worked on both platforms. In 1994 Rick ported
1069 to SVR4 and Solaris and wrote the
1070 automatic configuration support. In 1995 he ported
1073 and tired of writing about himself in the third person.
1075 Beginning with 1996,
1077 was maintained by Wichert Akkerman.
1080 development migrated to CVS; ports to FreeBSD and many architectures on Linux
1081 (including ARM, IA-64, MIPS, PA-RISC, PowerPC, s390, SPARC) were introduced.
1082 In 2002, the burden of
1084 maintainership was transferred to Ronald McGrath.
1087 gained support for several new Linux architectures (AMD64, s390x, SuperH),
1088 bi-architecture support for some of them, and received numerous additions and
1089 improvements in syscalls decoders on Linux;
1091 development migrated to
1096 is actively maintained by Dmitry Levin.
1098 gained support for AArch64, ARC, AVR32, Blackfin, Meta, Nios II, OpenSISC 1000,
1099 RISC-V, Tile/TileGx, Xtensa architectures since that time.
1100 In 2012, unmaintained and apparently broken support for non-Linux operating
1101 systems was removed.
1104 gained support for path tracing and file descriptor path decoding.
1105 In 2014, support for stack traces printing was added.
1106 In 2016, syscall fault injection was implemented.
1108 For the additional information, please refer to the
1112 repository commit log.
1116 should be reported to the
1118 mailing list at <strace\-devel@lists.strace.io>.
1120 .BR strace-log-merge (1),