说明：本文档简要描述了ltrace的命令，在文末有本命令的基本应用。

ltrace - A library call tracer

Trace library calls of a given program.

1。 -a, --align=COLUMN align return values in a secific column.

对齐具体某个列的返回值

2。 -c                  count time and calls, and report a summary on exit.

计算时间和调用，并在程序退出时打印摘要

3。 -C, --demangle      decode low-level symbol names into user-level names.

解码低级别名称（内核级）为用户级名称

4。 -d, --debug         print debugging info.

打印调试信息

5。 -e expr             modify which events to trace.

改变跟踪的事件

6。 -f                  follow forks.

跟踪子进程

7。 -h, --help          display this help and exit.

打印帮助信息

8。 -i                  print instruction pointer at time of library call.

打印指令指针，当库调用时

9。 -l, --library=FILE print library calls from this library only.

只打印某个库中的调用

10。 -L                  do NOT display library calls.

不打印库调用(注，不打印库调用信息，咱要你做什么呀)

11。 -n, --indent=NR     indent output by NR spaces for each call level nesting.

对每个调用级别嵌套以NR个空格进行缩进输出

12。 -o, --output=FILE   write the trace output to that file.

把输出定向到文件

13。 -p PID              attach to the process with the process ID pid.

附着在值为PID的进程号上进行ltrace

14。 -r                  print relative timestamps.

打印相对时间戳

15。 -s STRLEN           specify the maximum string size to print.

设置打印的字符串最大长度

16。 -S                  display system calls.

显示系统调用

17。 -t, -tt, -ttt       print absolute timestamps.

打印绝对时间戳

18。 -T                  show the time spent inside each call.

输出每个调用过程的时间开销

19。 -u USERNAME         run command with the userid, groupid of username.

使用某个用户ID或组ID来运行命令

20。 -V, --version       output version information and exit.

打印版本信息，然后退出

21。 -x NAME             treat the global NAME like a library subroutine.

----- 不好意思，这句话还真不知怎么翻译好 --------

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下面是常见的几种应用场景

1。最基本应用，不带任何参数

[guest@localhost tmp]$ ltrace ./a.out 

__libc_start_main(0x80484aa, 1, 0xbfc07744, 0x8048550, 0x8048540 <unfinished ...>

printf("no1:%d \t no2:%d \t diff:%d\n", 10, 6, 4no1:10   no2:6   diff:4 ) = 24

printf("no1:%d \t no2:%d \t diff:%d\n", 9, 7, 2no1:9     no2:7   diff:2 ) = 23

printf("no1:%d \t no2:%d \t diff:%d\n", 8, 8, 0no1:8     no2:8   diff:0 ) = 23

--- SIGFPE (Floating point exception) ---

+++ killed by SIGFPE +++

2。输出调用时间开销

[guest@localhost tmp]$ ltrace -T ./a.out 

__libc_start_main(0x80484aa, 1, 0xbf81d394, 0x8048550, 0x8048540 <unfinished ...>

printf("no1:%d \t no2:%d \t diff:%d\n", 10, 6, 4no1:10   no2:6   diff:4 ) = 24 <0.000972>

printf("no1:%d \t no2:%d \t diff:%d\n", 9, 7, 2no1:9     no2:7   diff:2 ) = 23 <0.000155>

printf("no1:%d \t no2:%d \t diff:%d\n", 8, 8, 0no1:8     no2:8   diff:0 ) = 23 <0.000153>

--- SIGFPE (Floating point exception) ---

+++ killed by SIGFPE +++

3。显示系统调用

[guest@localhost tmp]$ ltrace -S ./a.out 

SYS_brk(NULL)                                                                = 0x9e20000

SYS_access(0xa4710f, 4, 0xa4afc0, 0, 0xa4b644)                               = 0

SYS_open("/etc/ld.so.preload", 0, 02)                                        = 3

SYS_fstat64(3, 0xbfbd7a94, 0xa4afc0, -1, 3)                                  = 0

SYS_mmap2(0, 17, 3, 2, 3)                                                    = 0xb7f2a000

SYS_close(3)                                                                 = 0

SYS_open("/lib/libcwait.so", 0, 00)                                          = 3

SYS_read(3, "\177ELF\001\001\001", 512)                                      = 512

SYS_fstat64(3, 0xbfbd76fc, 0xa4afc0, 4, 0xa4b658)                            = 0

SYS_mmap2(0, 4096, 3, 34, -1)                                                = 0xb7f29000

SYS_mmap2(0, 5544, 5, 2050, 3)                                               = 0x423000

SYS_mmap2(0x424000, 4096, 3, 2066, 3)                                        = 0x424000 

.............省去若干行