strace

STRACE(1) General Commands Manual STRACE(1)

NAME

   strace - trace system calls and signals

SYNOPSIS

   strace [-ACdffhikqqrtttTvVwxxyyYzZ] [-a column] [-b execve] [-e expr]... [-I n] [-o file] [-O overhead] [-p pid]... [-P path]... [-s strsize] [-S sortby] [-U columns] [-X format]
          [--seccomp-bpf] [--stack-trace-frame-limit=limit] [--syscall-limit=limit] [--tips[=format]] { -p pid | [-DDD] [-E var[=val]]... [-u username] command [args] }

   strace -c [-dfwzZ] [-b execve] [-e expr]... [-I n] [-O overhead] [-p pid]... [-P path]... [-S sortby] [-U columns] [--seccomp-bpf] [--syscall-limit=limit] [--tips[=format]] { -p pid |
          [-DDD] [-E var[=val]]... [-u username] command [args] }

   strace --tips[=format]

DESCRIPTION

   In  the simplest case strace runs the specified command until it exits.  It intercepts and records the system calls which are called by a process and the signals which are received by
   a process.  The name of each system call, its arguments and its return value are printed on standard error or to the file specified with the -o option.

   strace is a useful diagnostic, instructional, and debugging tool.  System administrators, diagnosticians and trouble-shooters will find it invaluable for solving  problems  with  pro‐
   grams  for  which  the source is not readily available since they do not need to be recompiled in order to trace them.  Students, hackers and the overly-curious will find that a great
   deal can be learned about a system and its system calls by tracing even ordinary programs.  And programmers will find that since system calls and signals are events that happen at the
   user/kernel interface, a close examination of this boundary is very useful for bug isolation, sanity checking and attempting to capture race conditions.

   Each line in the trace contains the system call name, followed by its arguments in parentheses and its return value.  An example from stracing the command "cat /dev/null" is:

       open("/dev/null", O_RDONLY) = 3

   Errors (typically a return value of -1) have the errno symbol and error string appended.

       open("/foo/bar", O_RDONLY) = -1 ENOENT (No such file or directory)

   Signals are printed as signal symbol and decoded siginfo structure.  An excerpt from stracing and interrupting the command "sleep 666" is:

       sigsuspend([] <unfinished ...>
       --- SIGINT {si_signo=SIGINT, si_code=SI_USER, si_pid=...} ---
       +++ killed by SIGINT +++

   If a system call is being executed and meanwhile another one is being called from a different thread/process then strace will try to preserve the order of those events  and  mark  the
   ongoing call as being unfinished.  When the call returns it will be marked as resumed.

       [pid 28772] select(4, [3], NULL, NULL, NULL <unfinished ...>
       [pid 28779] clock_gettime(CLOCK_REALTIME, {tv_sec=1130322148, tv_nsec=3977000}) = 0
       [pid 28772] <... select resumed> )      = 1 (in [3])

   Interruption  of  a  (restartable) system call by a signal delivery is processed differently as kernel terminates the system call and also arranges its immediate reexecution after the
   signal handler completes.

       read(0, 0x7ffff72cf5cf, 1)              = ? ERESTARTSYS (To be restarted)
       --- SIGALRM {si_signo=SIGALRM, si_code=SI_KERNEL} ---
       rt_sigreturn({mask=[]})                 = 0
       read(0, "", 1)                          = 0

   Arguments are printed in symbolic form with passion.  This example shows the shell performing ">>xyzzy" output redirection:

       open("xyzzy", O_WRONLY|O_APPEND|O_CREAT, 0666) = 3

   Here, the second and the third argument of open(2) are decoded by breaking down the flag argument into its three bitwise-OR constituents and printing the mode value in octal by tradi‐
   tion.  Where the traditional or native usage differs from ANSI or POSIX, the latter forms are preferred.  In some cases, strace output is proven to be more readable than the source.

   Structure pointers are dereferenced and the members are displayed as appropriate.  In most cases, arguments are formatted in the  most  C-like  fashion  possible.   For  example,  the
   essence of the command "ls -l /dev/null" is captured as:

       lstat("/dev/null", {st_mode=S_IFCHR|0666, st_rdev=makedev(0x1, 0x3), ...}) = 0

   Notice  how  the  'struct stat' argument is dereferenced and how each member is displayed symbolically.  In particular, observe how the st_mode member is carefully decoded into a bit‐
   wise-OR of symbolic and numeric values.  Also notice in this example that the first argument to lstat(2) is an input to the system call and the second argument is  an  output.   Since
   output  arguments are not modified if the system call fails, arguments may not always be dereferenced.  For example, retrying the "ls -l" example with a non-existent file produces the
   following line:

       lstat("/foo/bar", 0xb004) = -1 ENOENT (No such file or directory)

   In this case the porch light is on but nobody is home.

   Syscalls unknown to strace are printed raw, with the unknown system call number printed in hexadecimal form and prefixed with "syscall_":

       syscall_0xbad(0x1, 0x2, 0x3, 0x4, 0x5, 0x6) = -1 ENOSYS (Function not implemented)

   Character pointers are dereferenced and printed as C strings.  Non-printing characters in strings are normally represented by ordinary C escape codes.  Only the first strsize  (32  by
   default)  bytes  of  strings  are  printed; longer strings have an ellipsis appended following the closing quote.  Here is a line from "ls -l" where the getpwuid(3) library routine is
   reading the password file:

       read(3, "root::0:0:System Administrator:/"..., 1024) = 422

   While structures are annotated using curly braces, pointers to basic types and arrays are printed using square brackets with commas separating the elements.  Here is an  example  from
   the command id(1) on a system with supplementary group ids:

       getgroups(32, [100, 0]) = 2

   On the other hand, bit-sets are also shown using square brackets, but set elements are separated only by a space.  Here is the shell, preparing to execute an external command:

       sigprocmask(SIG_BLOCK, [CHLD TTOU], []) = 0

   Here,  the  second  argument  is  a bit-set of two signals, SIGCHLD and SIGTTOU.  In some cases, the bit-set is so full that printing out the unset elements is more valuable.  In that
   case, the bit-set is prefixed by a tilde like this:

       sigprocmask(SIG_UNBLOCK, ~[], NULL) = 0

   Here, the second argument represents the full set of all signals.

OPTIONS General

   -e expr     A qualifying expression which modifies which events to trace or how to trace them.  The format of the expression is:

                         [qualifier=][!]value[,value]...

               where qualifier is one of trace (or t), trace-fds (or trace-fd or fd or fds), abbrev (or a), verbose (or v), raw (or x), signal (or signals or s), read (or  reads  or  r),
               write (or writes or w), fault, inject, status, quiet (or silent or silence or q), decode-fds (or decode-fd), decode-pids (or decode-pid), or kvm, and value is a qualifier-
               dependent  symbol  or  number.   The  default qualifier is trace.  Using an exclamation mark negates the set of values.  For example, -e open means literally -e trace=open
               which in turn means trace only the open system call.  By contrast, -e trace=!open means to trace every system call except open.  In addition, the special  values  all  and
               none have the obvious meanings.

               Note that some shells use the exclamation point for history expansion even inside quoted arguments.  If so, you must escape the exclamation point with a backslash.

Startup

   -E var=val
   --env=var=val
               Run command with var=val in its list of environment variables.

   -E var
   --env=var   Remove var from the inherited list of environment variables before passing it on to the command.

   -p pid
   --attach=pid
               Attach  to the process with the process ID pid and begin tracing.  The trace may be terminated at any time by a keyboard interrupt signal (CTRL-C).  strace will respond by
               detaching itself from the traced process(es) leaving it (them) to continue running.  Multiple -p options can be used to attach to many processes  in  addition  to  command
               (which  is optional if at least one -p option is given).  Multiple process IDs, separated by either comma (“,”), space (“ ”), tab, or newline character, can be provided as
               an argument to a single -p option, so, for example, -p "$(pidof PROG)" and -p "$(pgrep PROG)" syntaxes are supported.

   -u username
   --user=username
               Run command with the user ID, group ID, and supplementary groups of username.  This option is only useful when running as root and enables the correct execution of  setuid
               and/or setgid binaries.  Unless this option is used setuid and setgid programs are executed without effective privileges.
   -u UID:GID
   --user=UID:GID
               Alternative  syntax  where  the program is started with exactly the given user and group IDs, and an empty list of supplementary groups.  In this case, user and group name
               lookups are not performed.

   --argv0=name
               Set argv[0] of the command being executed to name.  Useful for tracing multi-call executables which interpret argv[0], such as busybox or kmod.

Tracing

   -b syscall
   --detach-on=syscall
               If specified syscall is reached, detach from traced process.  Currently, only execve(2) syscall is supported.  This option is useful if you want  to  trace  multi-threaded
               process and therefore require -f, but don't want to trace its (potentially very complex) children.

   -D
   --daemonize
   --daemonize=grandchild
               Run  tracer  process  as  a  grandchild,  not  as  the parent of the tracee.  This reduces the visible effect of strace by keeping the tracee a direct child of the calling
               process.

   -DD
   --daemonize=pgroup
   --daemonize=pgrp
               Run tracer process as tracee's grandchild in a separate process group.  In addition to reduction of the visible effect of strace, it also avoids  killing  of  strace  with
               kill(2) issued to the whole process group.

   -DDD
   --daemonize=session
               Run  tracer  process as tracee's grandchild in a separate session ("true daemonisation").  In addition to reduction of the visible effect of strace, it also avoids killing
               of strace upon session termination.

   -f
   --follow-forks
               Trace child processes as they are created by currently traced processes as a result of the fork(2), vfork(2) and clone(2) system calls.  Note that -p PID  -f  will  attach
               all threads of process PID if it is multi-threaded, not only thread with thread_id = PID.

   --output-separately
               If the --output=filename option is in effect, each processes trace is written to filename.pid where pid is the numeric process id of each process.

   -ff
   --follow-forks --output-separately
               Combine the effects of --follow-forks and --output-separately options.  This is incompatible with -c, since no per-process counts are kept.

               One might want to consider using strace-log-merge(1) to obtain a combined strace log view.

   -I interruptible
   --interruptible=interruptible
               When strace can be interrupted by signals (such as pressing CTRL-C).

               1, anywhere    no signals are blocked;
               2, waiting     fatal signals are blocked while decoding syscall (default);
               3, never       fatal signals are always blocked (default if -o FILE PROG);
               4, never_tstp  fatal signals and SIGTSTP (CTRL-Z) are always blocked (useful to make strace -o FILE PROG not stop on CTRL-Z, default if -D).

   --syscall-limit=limit
               Detach  all  tracees  when limit number of syscalls have been captured. Syscalls filtered out via --trace, --trace-path or --status options are not considered when keeping
               track of the number of syscalls that are captured.

   --kill-on-exit
               Apply PTRACE_O_EXITKILL ptrace option to all tracee processes (which sends a SIGKILL signal to the tracee if the tracer exits) and do not detach them on  cleanup  so  they
               will not be left running after the tracer exit.  --kill-on-exit is not compatible with -p/--attach options.

Filtering

   -e trace=syscall_set
   -e t=syscall_set
   --trace=syscall_set
               Trace only the specified set of system calls.  syscall_set is defined as [!]value[,value], and value can be one of the following:

               syscall      Trace specific syscall, specified by its name (see syscalls(2) for a reference, but also see NOTES).

               ?value       Question mark before the syscall qualification allows suppression of error in case no syscalls matched the qualification provided.

               value@64     Limit the syscall specification described by value to 64-bit personality.

               value@32     Limit the syscall specification described by value to 32-bit personality.

               value@x32    Limit the syscall specification described by value to x32 personality.

               all          Trace all system calls.

               /regex       Trace only those system calls that match the regex.  You can use POSIX Extended Regular Expression syntax (see regex(7)).

               %file
               file         Trace all system calls which take a file name as an argument.  You can think of this as an abbreviation for -e trace=open,stat,chmod,unlink,...  which is use‐
                            ful  to  seeing  what  files the process is referencing.  Furthermore, using the abbreviation will ensure that you don't accidentally forget to include a call
                            like lstat(2) in the list.  Betchya woulda forgot that one.  The syntax without a preceding percent sign ("-e trace=file") is deprecated.

               %process
               process      Trace system calls associated with process lifecycle (creation, exec, termination).  The syntax without a preceding percent sign ("-e trace=process") is  dep‐
                            recated.

               %net
               %network
               network      Trace all the network related system calls.  The syntax without a preceding percent sign ("-e trace=network") is deprecated.

               %signal
               signal       Trace all signal related system calls.  The syntax without a preceding percent sign ("-e trace=signal") is deprecated.

               %ipc
               ipc          Trace all IPC related system calls.  The syntax without a preceding percent sign ("-e trace=ipc") is deprecated.

               %desc
               desc         Trace all file descriptor related system calls.  The syntax without a preceding percent sign ("-e trace=desc") is deprecated.

               %memory
               memory       Trace all memory mapping related system calls.  The syntax without a preceding percent sign ("-e trace=memory") is deprecated.

               %creds       Trace system calls that read or modify user and group identifiers or capability sets.

               %stat        Trace stat syscall variants.

               %lstat       Trace lstat syscall variants.

               %fstat       Trace fstat, fstatat, and statx syscall variants.

               %%stat       Trace syscalls used for requesting file status (stat, lstat, fstat, fstatat, statx, and their variants).

               %statfs      Trace  statfs,  statfs64,  statvfs, osf_statfs, and osf_statfs64 system calls.  The same effect can be achieved with -e trace=/^(.*_)?statv?fs regular expres‐
                            sion.

               %fstatfs     Trace fstatfs, fstatfs64, fstatvfs, osf_fstatfs, and osf_fstatfs64 system calls.  The same effect can be achieved with -e trace=/fstatv?fs regular expression.

               %%statfs     Trace syscalls related to file system statistics (statfs-like, fstatfs-like, and ustat).  The same effect can be achieved with -e trace=/statv?fs|fsstat|ustat
                            regular expression.

               %clock       Trace system calls that read or modify system clocks.

               %pure        Trace syscalls that always succeed and have no arguments.  Currently, this  list  includes  arc_gettls(2),  getdtablesize(2),  getegid(2),  getegid32(2),  ge‐
                            teuid(2),  geteuid32(2), getgid(2), getgid32(2), getpagesize(2), getpgrp(2), getpid(2), getppid(2), get_thread_area(2) (on architectures other than x86), get‐
                            tid(2), get_tls(2), getuid(2), getuid32(2), getxgid(2), getxpid(2), getxuid(2), kern_features(2), and metag_get_tls(2) syscalls.

               The -c option is useful for determining which system calls might be useful to trace.  For example, trace=open,close,read,write means to only trace those four system calls.
               Be careful when making inferences about the user/kernel boundary if only a subset of system calls are being monitored.  The default is trace=all.

   -e trace-fd=set
   -e trace-fds=set
   -e fd=set
   -e fds=set
   --trace-fds=set
               Trace only the syscalls that operate on the specified subset of (non-negative) file descriptors.  Note that usage of this option also filters out all the syscalls that  do
               not operate on file descriptors at all.  Applies in (inclusive) disjunction with the --trace-path option.

   -e signal=set
   -e signals=set
   -e s=set
   --signal=set
               Trace only the specified subset of signals.  The default is signal=all.  For example, signal=!SIGIO (or signal=!io) causes SIGIO signals not to be traced.

   -e status=set
   --status=set
               Print only system calls with the specified return status.  The default is status=all.  When using the status qualifier, because strace waits for system calls to return be‐
               fore deciding whether they should be printed or not, the traditional order of events may not be preserved anymore.  If two system calls are executed by concurrent threads,
               strace  will first print both the entry and exit of the first system call to exit, regardless of their respective entry time.  The entry and exit of the second system call
               to exit will be printed afterwards.  Here is an example when select(2) is called, but a different thread calls clock_gettime(2) before select(2) finishes:

                   [pid 28779] 1130322148.939977 clock_gettime(CLOCK_REALTIME, {1130322148, 939977000}) = 0
                   [pid 28772] 1130322148.438139 select(4, [3], NULL, NULL, NULL) = 1 (in [3])

               set can include the following elements:

               successful   Trace system calls that returned without an error code.  The -z option has the effect of status=successful.
               failed       Trace system calls that returned with an error code.  The -Z option has the effect of status=failed.
               unfinished   Trace system calls that did not return.  This might happen, for example, due to an execve call in a neighbour thread.
               unavailable  Trace system calls that returned but strace failed to fetch the error status.
               detached     Trace system calls for which strace detached before the return.

   -P path
   --trace-path=path
               Trace only system calls accessing path.  Multiple -P options can be used to specify several paths.  Applies in (inclusive) disjunction with the --trace-fds option.

   -z
   --successful-only
               Print only syscalls that returned without an error code.

   -Z
   --failed-only
               Print only syscalls that returned with an error code.

Output format

   -a column
   --columns=column
               Align return values in a specific column (default column 40).

   -e abbrev=syscall_set
   -e a=syscall_set
   --abbrev=syscall_set
               Abbreviate the output from printing each member of large structures.  The syntax of the syscall_set specification is the same as in the -e trace option.   The  default  is
               abbrev=all.  The -v option has the effect of abbrev=none.

   -e verbose=syscall_set
   -e v=syscall_set
   --verbose=syscall_set
               Dereference  structures  for  the  specified  set of system calls.  The syntax of the syscall_set specification is the same as in the -e trace option.  The default is ver‐
               bose=all.

   -e raw=syscall_set
   -e x=syscall_set
   --raw=syscall_set
               Print raw, undecoded arguments for the specified set of system calls.  The syntax of the syscall_set specification is the same as in the -e trace option.  This option  has
               the effect of causing all arguments to be printed in hexadecimal.  This is mostly useful if you don't trust the decoding or you need to know the actual numeric value of an
               argument.  See also -X raw option.

   -e read=set
   -e reads=set
   -e r=set
   --read=set  Perform  a full hexadecimal and ASCII dump of all the data read from file descriptors listed in the specified set.  For example, to see all input activity on file descrip‐
               tors 3 and 5 use -e read=3,5.  Note that this is independent from the normal tracing of the read(2) system call which is controlled by the option -e trace=read.

   -e write=set
   -e writes=set
   -e w=set
   --write=set Perform a full hexadecimal and ASCII dump of all the data written to file descriptors listed in the specified set.  For example, to see all output  activity  on  file  de‐
               scriptors 3 and 5 use -e write=3,5.  Note that this is independent from the normal tracing of the write(2) system call which is controlled by the option -e trace=write.

   -e quiet=set
   -e silent=set
   -e silence=set
   -e q=set
   --quiet=set
   --silent=set
   --silence=set
               Suppress various information messages.  The default is quiet=none.  set can include the following elements:

               attach           Suppress messages about attaching and detaching ("[ Process NNNN attached ]", "[ Process NNNN detached ]").
               exit             Suppress messages about process exits ("+++ exited with SSS +++").
               path-resolution  Suppress messages about resolution of paths provided via the -P option ("Requested path "..." resolved into "..."").
               personality      Suppress messages about process personality changes ("[ Process PID=NNNN runs in PPP mode. ]").
               thread-execve
               superseded       Suppress messages about process being superseded by execve(2) in another thread ("+++ superseded by execve in pid NNNN +++").

   -e decode-fds=set
   --decode-fds=set
               Decode various information associated with file descriptors.  The default is decode-fds=none.  set can include the following elements:

               path     Print file paths.  Also enables printing of tracee's current working directory when AT_FDCWD constant is used.
               socket   Print socket protocol-specific information.
               dev      Print character/block device numbers.
               eventfd  Print eventfd object details associated with eventfd file descriptors.
               pidfd    Print PIDs associated with pidfd file descriptors.
               signalfd Print signal masks associated with signalfd file descriptors.

   -e decode-pids=set
   --decode-pids=set
               Decode  various  information  associated with process IDs (and also thread IDs, process group IDs, and session IDs).  The default is decode-pids=none.  set can include the
               following elements:

               comm    Print command names associated with thread or process IDs.
               pidns   Print thread, process, process group, and session IDs in strace's PID namespace if the tracee is in a different PID namespace.

   -e kvm=vcpu
   --kvm=vcpu  Print the exit reason of kvm vcpu.  Requires Linux kernel version 4.16.0 or higher.

   -i
   --instruction-pointer
               Print the instruction pointer at the time of the system call.

   -n
   --syscall-number
               Print the syscall number.

   -k
   --stack-trace[=symbol]
               Print the execution stack trace of the traced processes after each system call.

   --stack-trace-frame-limit=limit
               Print no more than this amount of stack trace frames when backtracing a system call (the default is 256).  Use this option with the --stack-trace (or -k) option.

   -o filename
   --output=filename
               Write the trace output to the file filename rather than to stderr.  filename.pid form is used if -ff option is supplied.  If the argument begins with '|' or '!', the  rest
               of  the argument is treated as a command and all output is piped to it.  This is convenient for piping the debugging output to a program without affecting the redirections
               of executed programs.  The latter is not compatible with -ff option currently.

   -A
   --output-append-mode
               Open the file provided in the -o option in append mode.

   -q
   --quiet
   --quiet=attach,personality
               Suppress messages about attaching, detaching, and personality changes.  This happens automatically when output is redirected to a file and the command is run directly  in‐
               stead of attaching.

   -qq
   --quiet=attach,personality,exit
               Suppress messages attaching, detaching, personality changes, and about process exit status.

   -qqq
   --quiet=all Suppress all suppressible messages (please refer to the -e quiet option description for the full list of suppressible messages).

   -r
   --relative-timestamps[=precision]
               Print  a  relative timestamp upon entry to each system call.  This records the time difference between the beginning of successive system calls.  precision can be one of s
               (for seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds), and allows setting the precision of time value being  printed.   Default  is  us  (microseconds).
               Note  that since -r option uses the monotonic clock time for measuring time difference and not the wall clock time, its measurements can differ from the difference in time
               reported by the -t option.

   -s strsize
   --string-limit=strsize
               Specify the maximum string size to print (the default is 32).  Note that filenames are not considered strings and are always printed in full.

   --absolute-timestamps[=[[format:]format],[[precision:]precision]]
   --timestamps[=[[format:]format],[[precision:]precision]]
               Prefix each line of the trace with the wall clock time in the specified format with the specified precision.  format can be one of the following:

               none          No time stamp is printed.  Can be used to override the previous setting.
               time          Wall clock time (strftime(3) format string is %T).
               unix          Number of seconds since the epoch (strftime(3) format string is %s).

               precision can be one of s (for seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds).  Default arguments for the option are format:time,precision:s.

   -t
   --absolute-timestamps
               Prefix each line of the trace with the wall clock time.

   -tt
   --absolute-timestamps=precision:us
               If given twice, the time printed will include the microseconds.

   -ttt
   --absolute-timestamps=format:unix,precision:us
               If given thrice, the time printed will include the microseconds and the leading portion will be printed as the number of seconds since the epoch.

   -T
   --syscall-times[=precision]
               Show the time spent in system calls.  This records the time difference between the beginning and the end of each system call.  precision can be one of s (for seconds),  ms
               (milliseconds), us (microseconds), or ns (nanoseconds), and allows setting the precision of time value being printed.  Default is us (microseconds).

   -v
   --no-abbrev Print  unabbreviated versions of environment, stat, termios, etc.  calls.  These structures are very common in calls and so the default behavior displays a reasonable sub‐
               set of structure members.  Use this option to get all of the gory details.

   --strings-in-hex[=option]
               Control usage of escape sequences with hexadecimal numbers in the printed strings.  Normally (when no --strings-in-hex or -x option is supplied), escape sequences are used
               to print non-printable and non-ASCII characters (that is, characters with a character code less than 32 or greater than 127), or to disambiguate the output (so, for quotes
               and other characters that encase the printed string, for example, angle brackets, in case of file descriptor path output); for the former use case, unless it  is  a  white
               space  character that has a symbolic escape sequence defined in the C standard (that is, “\t” for a horizontal tab, “\n” for a newline, “\v” for a vertical tab, “\f” for a
               form feed page break, and “\r” for a carriage return) are printed using escape sequences with numbers that correspond to their byte values, with octal number format  being
               the default.  option can be one of the following:

               none             Hexadecimal numbers are not used in the output at all.  When there is a need to emit an escape sequence, octal numbers are used.
               non-ascii-chars  Hexadecimal numbers are used instead of octal in the escape sequences.
               non-ascii        Strings that contain non-ASCII characters are printed using escape sequences with hexadecimal numbers.
               all              All strings are printed using escape sequences with hexadecimal numbers.

               When the option is supplied without an argument, all is assumed.

   -x
   --strings-in-hex=non-ascii
               Print all non-ASCII strings in hexadecimal string format.

   -xx
   --strings-in-hex[=all]
               Print all strings in hexadecimal string format.

   -X format
   --const-print-style=format
               Set the format for printing of named constants and flags.  Supported format values are:

               raw       Raw number output, without decoding.
               abbrev    Output a named constant or a set of flags instead of the raw number if they are found.  This is the default strace behaviour.
               verbose   Output both the raw value and the decoded string (as a comment).

   -y
   --decode-fds
   --decode-fds=path
               Print paths associated with file descriptor arguments and with the AT_FDCWD constant.

   -yy
   --decode-fds=all
               Print  all available information associated with file descriptors: protocol-specific information associated with socket file descriptors, block/character device number as‐
               sociated with device file descriptors, and PIDs associated with pidfd file descriptors.

   --pidns-translation
   --decode-pids=pidns
               If strace and tracee are in different PID namespaces, print PIDs in strace's namespace, too.

   -Y
   --decode-pids=comm
               Print command names for PIDs.

   --always-show-pid
               Show PID prefix also for the process started by strace.  Implied when -f and -o are both specified.

Statistics

   -c
   --summary-only
               Count time, calls, and errors for each system call and report a summary on program exit, suppressing the regular output.  This attempts to show system time (CPU time spent
               running in the kernel) independent of wall clock time.  If -c is used with -f, only aggregate totals for all traced processes are kept.

   -C
   --summary   Like -c but also print regular output while processes are running.

   -O overhead
   --summary-syscall-overhead=overhead
               Set the overhead for tracing system calls to overhead.  This is useful for overriding the default heuristic for guessing how much time is spent in mere measuring when tim‐
               ing system calls using the -c option.  The accuracy of the heuristic can be gauged by timing a given program run without tracing (using time(1)) and comparing the  accumu‐
               lated system call time to the total produced using -c.

               The format of overhead specification is described in section Time specification format description.

   -S sortby
   --summary-sort-by=sortby
               Sort  the  output  of the histogram printed by the -c option by the specified criterion.  Legal values are time (or time-percent or time-total or total-time), min-time (or
               shortest or time-min), max-time (or longest or time-max), avg-time (or time-avg), calls (or count), errors (or error), name (or syscall or syscall-name), and  nothing  (or
               none); default is time.

   -U columns
   --summary-columns=columns
               Configure a set (and order) of columns being shown in the call summary.  The columns argument is a comma-separated list with items being one of the following:

               time-percent (or time)              Percentage of cumulative time consumed by a specific system call.
               total-time (or time-total)          Total system (or wall clock, if -w option is provided) time consumed by a specific system call.
               min-time (or shortest or time-min)  Minimum observed call duration.
               max-time (or longest or time-max)   Maximum observed call duration.
               avg-time (or time-avg)              Average call duration.
               calls (or count)                    Call count.
               errors (or error)                   Error count.
               name (or syscall or syscall-name)   Syscall name.

               The default value is time-percent,total-time,avg-time,calls,errors,name.  If the name field is not supplied explicitly, it is added as the last column.

   -w
   --summary-wall-clock
               Summarise the time difference between the beginning and end of each system call.  The default is to summarise the system time.