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 --------
#########################################################################################
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