strace
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strace[1] is a diagnostic, debugging and instructional userspace utility for Linux that allows to trace system calls and signals.
strace -c -f -p $PID .../... % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 63.56 0.032899 539 61 13 futex 17.62 0.009118 217 42 epoll_pwait 11.48 0.005944 104 57 nanosleep 3.15 0.001628 11 142 madvise 1.07 0.000553 79 7 read 0.87 0.000452 64 7 write 0.72 0.000374 374 1 1 restart_syscall 0.59 0.000307 51 6 sched_yield 0.56 0.000291 145 2 getpid 0.36 0.000184 92 2 rt_sigreturn 0.01 0.000007 3 2 tgkill ------ ----------- ----------- --------- --------- ---------------- 100.00 0.051757 329 14 total
help
strace -help
usage: strace [-CdffhiqrtttTvVwxxy] [-I n] [-e expr]...
[-a column] [-o file] [-s strsize] [-P path]...
-p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]
or: strace -c[dfw] [-I n] [-e expr]... [-O overhead] [-S sortby]
-p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]
Output format:
-a column alignment COLUMN for printing syscall results (default 40)
-i print instruction pointer at time of syscall
-k obtain stack trace between each syscall
-o file send trace output to FILE instead of stderr
-q suppress messages about attaching, detaching, etc.
-r print relative timestamp
-s strsize limit length of print strings to STRSIZE chars (default 32)
-t print absolute timestamp
-tt print absolute timestamp with usecs
-T print time spent in each syscall
-x print non-ascii strings in hex
-xx print all strings in hex
-X format set the format for printing of named constants and flags
-y print paths associated with file descriptor arguments
-yy print protocol specific information associated with socket file descriptors
Statistics:
-c count time, calls, and errors for each syscall and report summary
-C like -c but also print regular output
-O overhead set overhead for tracing syscalls to OVERHEAD usecs
-S sortby sort syscall counts by: time, calls, name, nothing (default time)
-w summarise syscall latency (default is system time)
Filtering:
-e expr a qualifying expression: option=[!]all or option=[!]val1[,val2]...
options: trace, abbrev, verbose, raw, signal, read, write, fault, inject, kvm
-P path trace accesses to path
Tracing:
-b execve detach on execve syscall
-D run tracer process as a detached grandchild, not as parent
-f follow forks
-ff follow forks with output into separate files
-I interruptible
1: no signals are blocked
2: fatal signals are blocked while decoding syscall (default)
3: fatal signals are always blocked (default if '-o FILE PROG')
4: fatal signals and SIGTSTP (^Z) are always blocked
(useful to make 'strace -o FILE PROG' not stop on ^Z)
Startup:
-E var remove var from the environment for command
-E var=val put var=val in the environment for command
-p pid trace process with process id PID, may be repeated
-u username run command as username handling setuid and/or setgid
Miscellaneous:
-d enable debug output to stderr
-v verbose mode: print unabbreviated argv, stat, termios, etc. args
-h print help message
-V print version
Examples
See also
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