「strace」の版間の差分

2015年9月22日 (火) 16:49時点における最新版

strace とは、システムコールとシグナルをトレースするためのLinuxのコマンドです。

読み方

strace

えすとれーす

概要

strace とは、システムコールとシグナルをトレースするためのLinuxのコマンドです。

FreeBSD では、ktrace をご利用下さい。

インストール

Linux のデフォルトのコマンドです。

書式

usage: strace [-dDffhiqrtttTvVxx] [-a column] [-e expr] ... [-o file]
              [-p pid] ... [-s strsize] [-u username] [-E var=val] ...
              [command [arg ...]]
   or: strace -c [-D] [-e expr] ... [-O overhead] [-S sortby] [-E var=val] ...
              [command [arg ...]]
-c -- count time, calls, and errors for each syscall and report summary
-f -- follow forks, -ff -- with output into separate files
-F -- attempt to follow vforks, -h -- print help message
-i -- print instruction pointer at time of syscall
-q -- suppress messages about attaching, detaching, etc.
-r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs
-T -- print time spent in each syscall, -V -- print version
-v -- verbose mode: print unabbreviated argv, stat, termio[s], etc. args
-x -- print non-ascii strings in hex, -xx -- print all strings in hex
-a column -- alignment COLUMN for printing syscall results (default 40)
-e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...
   options: trace, abbrev, verbose, raw, signal, read, or write
-o file -- send trace output to FILE instead of stderr
-O overhead -- set overhead for tracing syscalls to OVERHEAD usecs
-p pid -- trace process with process id PID, may be repeated
-D -- run tracer process as a detached grandchild, not as parent
-s strsize -- limit length of print strings to STRSIZE chars (default 32)
-S sortby -- sort syscall counts by: time, calls, name, nothing (default time)
-u username -- run command as username handling setuid and/or setgid
-E var=val -- put var=val in the environment for command
-E var -- remove var from the environment for command

使い方

コマンドを指定する場合は、下記の通りです。

$ strace /path/to/command

プロセスID 123 をトレースする場合は、下記の通りです。

$ strace -p 123

cat コマンドをトレースする例です。

$ strace cat /etc/centos-release
execve("/bin/cat", ["cat", "/etc/centos-release"], [/* 29 vars */]) = 0
brk(0)                                  = 0x1c73000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9a4b96a000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=52696, ...}) = 0
mmap(NULL, 52696, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9a4b95d000
close(3)                                = 0
open("/lib64/libc.so.6", O_RDONLY)      = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360\355\1M6\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1922152, ...}) = 0
mmap(0x364d000000, 3745960, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x364d000000
mprotect(0x364d18a000, 2093056, PROT_NONE) = 0
mmap(0x364d389000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x189000) = 0x364d389000
mmap(0x364d38e000, 18600, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x364d38e000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9a4b95c000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9a4b95b000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9a4b95a000
arch_prctl(ARCH_SET_FS, 0x7f9a4b95b700) = 0
mprotect(0x364d389000, 16384, PROT_READ) = 0
mprotect(0x364ce1f000, 4096, PROT_READ) = 0
munmap(0x7f9a4b95d000, 52696)           = 0
brk(0)                                  = 0x1c73000
brk(0x1c94000)                          = 0x1c94000
open("/usr/lib/locale/locale-archive", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=99158576, ...}) = 0
mmap(NULL, 99158576, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9a45ac9000
close(3)                                = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
open("/etc/centos-release", O_RDONLY)   = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=27, ...}) = 0
read(3, "CentOS release 6.4 (Final)\n", 32768) = 27
write(1, "CentOS release 6.4 (Final)\n", 27CentOS release 6.4 (Final)
) = 27
read(3, "", 32768)                      = 0
close(3)                                = 0
close(1)                                = 0
close(2)                                = 0
exit_group(0)                           = ?

関連項目

• システムモニタリングツール
• ktrace