oracle自身已经提供了很多这类型的工具，如oradebug、各种等待事件和跟踪方式。此外，各类型的操作系统提供出很多系统级别工具，
所谓操作系统，是应用程序与服务器硬件进行沟通的中间层。应用程序的所有操作，都是和操作系统进行沟通交互。操作系统负责将所有交互转化为设备语言，进行硬件交互。
我们在进行oracle故障调试和内核原理工作的时候，经常需要了解后台运行的动作和细节。一些故障场景，如程序进程hang住、无法登陆等问题，就需要操作系统级别监控，检查定位问题。
oracle自身已经提供了很多这类型的工具，如oradebug、各种等待事件和跟踪方式。此外，各类型的操作系统提供出很多系统级别工具，帮助我们进行监控。本篇主要介绍linux环境中的strace工具典型使用方法，留待需要朋友待查。
1、环境介绍
笔者使用红帽red hat 6.5进行测试。
[root@xxx-standby-asm ~]# cat /etc/redhat-release
red hat enterprise linux server release 6.5 (santiago)
[root@xxx-standby-asm ~]# uname -a
linux xxx-standby-asm 2.6.32-431.el6.x86_64 #1 smp sun nov 10 22:19:54 est 2013 x86_64 x86_64 x86_64 gnu/linux
对应使用oracle版本为11.2.0.4。
[oracle@xxx-standby-asm ~]$ sqlplus /nolog
sql*plus: release 11.2.0.4.0 production on tue jun 16 16:39:21 2015
copyright (c) 1982, 2013, oracle.  all rights reserved.
sql> conn / as sysdba
connected.
sql> select * from v$version;
banner
--------------------------------------------------------------------------------
oracle database 11g enterprise edition release 11.2.0.4.0 - 64bit production
pl/sql release 11.2.0.4.0 - production
core    11.2.0.4.0      production
tns for linux: version 11.2.0.4.0 - production
nlsrtl version 11.2.0.4.0 – production
2、strace命令信息
使用-h参数，可以调用出strace命令的语法格式和各个使用参数。
[oracle@xxx-standby-asm ~]$ strace -h
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
在诸多参数中，比较常用的有如下几个：
ü  -t参数：可以显示调用操作系统过程的时间。这个在诊断中很重要，如果发现某一个执行过程时间消耗大，就可以定位到是什么问题；
ü  -p参数：strace除了可以从进程启动时候开始监控之外，还可以根据操作系统进程编号，进入一个运行中的进程进行debug；
ü  -o参数：输出结果如果需要以文件方式保存，就通过-o参数指定文件名称；
ü  -e参数：监控表达式。提供trace、signal、read和write等内容，反映监控方面项目。常用的参数是trace=file，集中在操作系统文件访问层面。
下面，通过两个典型应用场景，来演示一下strace应用。
3、启动程序监控
strace监控研究的一个重要范例是sqlplus，很多前辈使用这个工具来测试跟踪sqlplus启动过程访问的文件形式。启动strace监控sqlplus，就是在strace命令后直接输入sqlplus命令即可。
--启动命令
[oracle@localhost ~]$ strace -t -e trace=file sqlplus /nolog
14:21:14 execve(/u01/app/oracle/bin/sqlplus, [sqlplus, /nolog], [/* 31 vars */]) = 0 –启动命令
14:21:14 access(/etc/ld.so.preload, r_ok) = -1 enoent (no such file or directory)
14:21:14 open(/u01/app/oracle/lib/tls/x86_64/libsqlplus.so, o_rdonly) = -1 enoent (no such file or directory)
14:21:14 stat(/u01/app/oracle/lib/tls/x86_64, 0x7fff3076da50) = -1 enoent (no such file or directory)
14:21:14 open(/u01/app/oracle/lib/tls/libsqlplus.so, o_rdonly) = -1 enoent (no such file or directory)
14:21:14 stat(/u01/app/oracle/lib/tls, 0x7fff3076da50) = -1 enoent (no such file or directory)
14:21:14 open(/u01/app/oracle/lib/x86_64/libsqlplus.so, o_rdonly) = -1 enoent (no such file or directory)
14:21:14 stat(/u01/app/oracle/lib/x86_64, 0x7fff3076da50) = -1 enoent (no such file or directory)
14:21:14 open(/u01/app/oracle/lib/libsqlplus.so, o_rdonly) = 3
14:21:14 open(/u01/app/oracle/lib/libclntsh.so.11.1, o_rdonly) = 3
14:21:14 open(/u01/app/oracle/lib/libnnz11.so, o_rdonly) = 3
14:21:14 open(/u01/app/oracle/lib/libdl.so.2, o_rdonly) = -1 enoent (no such file or directory)
（篇幅原因，有省略……）
14:21:14 access(/etc/tnsnav.ora, f_ok) = -1 enoent (no such file or directory)
14:21:14 access(/u01/app/oracle/network/admin/tnsnav.ora, f_ok) = -1 enoent (no such file or directory)
14:21:14 open(/u01/app/oracle/oracore/zoneinfo, o_rdonly|o_nonblock|o_directory|o_cloexec) = 6
14:21:14 open(/u01/app/oracle/oracore/zoneinfo/timezlrg_1.dat, o_rdonly) = 7
14:21:14 open(/u01/app/oracle/oracore/zoneinfo/timezlrg_2.dat, o_rdonly) = 7
（读取各种时区数据……）
14:21:14 open(/u01/app/oracle/oracore/zoneinfo/timezone_14.dat, o_rdonly) = 7
14:21:14 open(/u01/app/oracle/oracore/zoneinfo/timezlrg_14.dat, o_rdonly) = 6
14:21:14 open(/usr/lib64/libnuma.so, o_rdonly) = -1 enoent (no such file or directory)
14:21:14 open(/usr/lib64/libnuma.so.1, o_rdonly) = 6
14:21:14 open(/proc/self/status, o_rdonly) = 6
14:21:14 open(/sys/devices/system/node, o_rdonly|o_nonblock|o_directory|o_cloexec) = 6
14:21:14 open(/sys/devices/system/node/node0/meminfo, o_rdonly) = 7
14:21:14 open(/sys/devices/system/cpu, o_rdonly|o_nonblock|o_directory|o_cloexec) = 6
14:21:14 open(/proc/self/status, o_rdonly) = 6
14:21:14 open(/proc/sys/kernel/shmmax, o_rdonly) = 6
14:21:14 open(/proc/meminfo, o_rdonly) = 6
14:21:14 open(/usr/lib64/libnuma.so, o_rdonly) = -1 enoent (no such file or directory)
14:21:14 open(/etc/localtime, o_rdonly) = 6
14:21:14 open(/u01/app/oracle/rdbms/mesg/ocius.msb, o_rdonly) = 6
sql*plus: release 11.2.0.4.0 production on fri jun 12 14:21:14 2015
copyright (c) 1982, 2013, oracle.  all rights reserved.
--启动之后，读取的文件。
14:21:14 stat(login.sql, 0x7fff3076c740) = -1 enoent (no such file or directory)
14:21:14 stat(/u01/app/oracle/sqlplus/admin/glogin.sql, {st_mode=s_ifreg|0644, st_size=368, ...}) = 0
14:21:14 access(/u01/app/oracle/sqlplus/admin/glogin.sql, f_ok) = 0