What is the use of the ltrace command in Linux
Editor to share with you what is the use of the ltrace command in Linux, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!
The ltrace command, which is commonly used in Linux, is used to track when a process calls library functions.
Ltrace is used to track when a process calls library functions.
Syntax ltrace [option...] [command [arg...]] Option-an aligns the return value of a specific column. -c calculates the time and call, and prints a summary when the program exits. -C decodes the low-level name (kernel level) as the user-level name. -d print debugging information. -e changes the tracked event. -f track child processes. -h print help information. -I print the instruction pointer when the library is called. -l prints only calls in a library. -L does not print library calls. -n,-- indent=NR indents each call level with NR spaces. -o,-- output=file directs the output to a file. -p PID is attached to the process number with the value PID for ltrace. -r prints a relative timestamp. -s STRLEN sets the maximum length of the printed string. -S displays the system call. -t,-tt,-ttt prints an absolute timestamp. -T outputs the time cost of each calling procedure. -u USERNAME uses a user id or group ID to run the command. -V,-- version prints version information, and then exits. -x NAME treat the global NAME like a library subroutine. (for translation) the most basic application of an example, without any parameters:
[guest@localhost tmp] $ltrace. / a.out _ libc_start_main (0x80484aa, 1, 0xbfc07744, 0x8048550, 0x8048540 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 + output call time cost:
[guest@localhost tmp] $ltrace-T. / a.out _ libc_start_main (0x80484aa, 1, 0xbf81d394, 0x8048550, 0x8048540 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 + displays the system call:
[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) 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. Omitting a few lines is all the content of the article "what is the use of ltrace commands in Linux?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!
