1、简介
strace是Linux环境下的一款程序调试工具，用来检察一个应用程序所使用的系统调用。Strace是一个简单的跟踪系统调用执行的工具。在其最简单的形式中，它可以从开始到结束跟踪二进制的执行，并在进程的生命周期中输出一行具有系统调用名称，每个系统调用的参数和返回值的文本行。
2、安装
官方网址：http://sourceforge.net/project/showfiles.php?group_id=2861&package_id=2819
[root@RedHat_test ~]# yum install strace
3、strace命令常用格式
[root@RedHat_test ~]# man strace
-tt : 在每行输出的前面，显示毫秒级别的时间
-T : 显示每次系统调用所花费的时间
-v : 对于某些相关调用，把完整的环境变量，文件stat结构等打出来。
-f : 跟踪目标进程，以及目标进程创建的所有子进程
-e : 控制要跟踪的事件和跟踪行为,比如指定要跟踪的系统调用名称
-o : 把strace的输出单独写到指定的文件
-s : 当系统调用的某个参数是字符串时，最多输出指定长度的内容，默认是32个字节
-p : 指定要跟踪的进程pid, 要同时跟踪多个pid, 重复多次-p选项即可。
4、跟踪ls命令
[root@RedHat_test opt]# strace ls
execve("/bin/ls", ["ls"], [/*46vars */])=0
brk(0)=0x1ab9000
access("/etc/ld.so.nohwcap", F_OK)=-1ENOENT (No such file or directory)
mmap(NULL,8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,-1,0)=0x7fcf695fb000
access("/etc/ld.so.preload", R_OK)=-1ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)=3
fstat(3,{st_mode=S_IFREG|0644,st_size=102786, ...})=0
mmap(NULL,102786, PROT_READ, MAP_PRIVATE,3,0)=0x7fcf695e1000
close(3)=0
access("/etc/ld.so.nohwcap", F_OK)=-1ENOENT (No such file or directory)
open("/lib/librt.so.1", O_RDONLY)=3
5、寻找被程序读取的php配置文件
[root@RedHat_test ~]# strace php 2>&1 | grep php.ini
6、跟踪指定的系统调用
[root@RedHat_test ~]# strace -e open cat dead.letter
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC)=3
open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC)=3
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC)=3
open("dead.letter", O_RDONLY)=-1ENOENT (No such file or directory)
cat: dead.letteropen("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC)=3
open("/usr/share/locale/zh_CN.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY)=-1ENOENT (No such file or directory)
open("/usr/share/locale/zh_CN.utf8/LC_MESSAGES/libc.mo", O_RDONLY)=-1ENOENT (No such file or directory)
open("/usr/share/locale/zh_CN/LC_MESSAGES/libc.mo", O_RDONLY)=3
open("/usr/lib64/gconv/gconv-modules.cache", O_RDONLY)=3
: 没有那个文件或目录
+++exited with1+++
7、跟踪进程
[root@RedHat_test ~]# strace -p 2208
strace: Process2208attached
restart_syscall(<... resuming interrupted poll ...>
)=1
read(5,"\1\0\0\0\0\0\0\0",16)=8
futex(0x560eaba76640, FUTEX_WAKE_PRIVATE,1)=1
poll([{fd=5,events=POLLIN},{fd=8,events=POLLIN}],2,-1)=1([{fd=5,revents=POLLIN}])
read(5,"\1\0\0\0\0\0\0\0",16)=8
poll([{fd=5,events=POLLIN},{fd=8,events=POLLIN}],2,-1)=1([{fd=5,revents=POLLIN}])
read(5,"\1\0\0\0\0\0\0\0",16)=8
poll([{fd=5,events=POLLIN},{fd=8,events=POLLIN}],2,-1)=1([{fd=8,revents=POLLIN}])
write(5,"\1\0\0\0\0\0\0\0",8)=8
write(7,"\1\0\0\0\0\0\0\0",8)=8
futex(0x560eaba6b9e0, FUTEX_WAKE_PRIVATE,1)=1
futex(0x560eaba861c0, FUTEX_WAKE_PRIVATE,1)=1
futex(0x560eaba6d198, FUTEX_WAKE_PRIVATE,1)=1
poll([{fd=8,events=POLLIN}],1,0)=1([{fd=8,revents=POLLIN}])
read(8,"\2\0\0\0\200\0\0\0}\327\5\0\20\0\0\00018452\0\0\0\0\0\0\0\0\0\0\0"...,2048)=64
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常见使用方法
[root@RedHat_test ~]# strace -T -e access -p 2208
----------------------------------------------------------------------------------------
8、统计跟踪结果的概要
[root@RedHat_test ~]# strace -c ls
1.pyfile.logscripts tsar
correct jdk-8u91-linux-x64.tar.gz test yunweimao
% time seconds usecs/call calls errors syscall
--------------------------------------------------------------
26.430.0003151227mmap
15.520.0001851910open
9.980.000119718mprotect
6.710.000080108read
6.710.000080613close
6.210.000074711fstat
4.450.000053272munmap
3.860.000046232statfs
2.850.000034341stat
2.680.000032162getdents
2.600.000031311openat
2.180.000026132write
2.100.0000251321access
1.850.000022221set_tid_address
1.590.00001963brk
1.260.00001582ioctl
1.010.00001262rt_sigaction
0.590.00000771execve
0.500.00000661getrlimit
0.500.00000661set_robust_list
0.420.00000551rt_sigprocmask
0.000.00000001arch_prctl
--------------------------------------------------------------
100.000.0011921121total
9、保存输出结果
[root@RedHat_test ~]# strace -o process_strace -p 2208
[root@RedHat_test ~]# ls
process_strace
[root@RedHat_test ~]# tail -f 10 process_strace
tail: 无法打开"100"读取数据: 没有那个文件或目录
==> process_strace <==
futex(0x560eaba6b9e0, FUTEX_WAKE_PRIVATE,1)=1
futex(0x560eaba861c0, FUTEX_WAKE_PRIVATE,1)=1
futex(0x560eaba6d198, FUTEX_WAKE_PRIVATE,1)=1
poll([{fd=8,events=POLLIN}],1,0)=1([{fd=8,revents=POLLIN}])
read(8,"\2\0\0\0\0\2\0\0\0\0\0\0\20\0\0\00018457\0\0\0\0\0\0\0\0\0\0\0"...,2048)=64
poll([{fd=8,events=POLLIN}],1,0)=0(Timeout)
write(5,"\1\0\0\0\0\0\0\0",8)=8
poll([{fd=5,events=POLLIN},{fd=8,events=POLLIN}],2,-1)=1([{fd=5,revents=POLLIN}])
read(5,"\2\0\0\0\0\0\0\0",16)=8
poll([{fd=5,events=POLLIN},{fd=8,events=POLLIN}],2,-1
10、跟踪nginx, 看其启动时都访问了哪些文件
[root@RedHat_test ~]# strace -tt -T -f -e trace=file -o /data/log/strace.log -s 1024 service nginx restart
[root@RedHat_test ~]# cat /data/log/strace.log
3259713:51:52.873281 execve("/usr/sbin/service", ["service","nginx","restart"], [/*27vars */])=0<0.000319>
3259713:51:52.874064 access("/etc/ld.so.preload", R_OK)=-1ENOENT (No such file or directory) <0.000017>
3259713:51:52.874184 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC)=3<0.000017>
3259713:51:52.874343 open("/lib64/libtinfo.so.5", O_RDONLY|O_CLOEXEC)=3<0.000017>
3259713:51:52.874549 open("/lib64/libdl.so.2", O_RDONLY|O_CLOEXEC)=3<0.000017>
3259713:51:52.874750 open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC)=3<0.000017>
# 每一行输出的最后尖括号中的数据表示执行耗时，单位是秒
11、显示时间戳
[root@RedHat_test ~]# strace -t ls
11:48:02 execve("/usr/bin/ls", ["ls"], [/*27vars */])=0
11:48:02 brk(NULL)=0x23ba000
11:48:02 mmap(NULL,4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,-1,0)=0x7fa562bae000
11:48:02 access("/etc/ld.so.preload", R_OK)=-1ENOENT (No such file or directory)
11:48:02 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC)=3
11:48:02 fstat(3,{st_mode=S_IFREG|0644,st_size=35957, ...})=0
11:48:02 mmap(NULL,35957, PROT_READ, MAP_PRIVATE,3,0)=0x7fa562ba5000
11:48:02 close(3)=0
11:48:02 open("/lib64/libselinux.so.1", O_RDONLY|O_CLOEXEC)=3
11:48:02 read(3,"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320i\0\0\0\0\0\0"...,832)=832
11:48:02 fstat(3,{st_mode=S_IFREG|0755,st_size=155784, ...})=0
11:48:02 mmap(NULL,2255184, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE,3,0)=0x7fa562767000
11:48:02 mprotect(0x7fa56278b000,2093056, PROT_NONE)=0
11:48:02 mmap(0x7fa56298a000,8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE,3, 0x23000)=0x7fa56298a000
11:48:02 mmap(0x7fa56298c000,6480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,-1,0)=0x7fa56298c000
11:48:02 close(3)=0
11:48:02 open("/lib64/libcap.so.2", O_RDONLY|O_CLOEXEC)=3
11:48:02 read(3,"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \26\0\0\0\0\0\0"...,832)=832
11:48:02 fstat(3,{st_mode=S_IFREG|0755,st_size=20032, ...})=0
----------------------------------------------------------------------------------------
-tt : 展示微秒级别的时间戳
[root@RedHat_test ~]# strace -tt ls
-ttt : 展示微秒级的时间戳，但是它并不是打印当前时间，而是显示自从epoch（译注：1970年1月1日00:00:00 UTC）以来的所经过的秒数
[root@RedHat_test ~]# strace -ttt ls
-r : 展示相对时间戳
[root@RedHat_test ~]# strace -r ls
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