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.
-c count time, calls, and errors for each syscall and report summary
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[edit]
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[edit]
See also[edit]
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