From 1bce9395b31799bfc4eec090b3f214789f3a3b65 Mon Sep 17 00:00:00 2001 From: linlongchen Date: Thu, 26 Mar 2020 20:45:26 +0800 Subject: [PATCH] update linux --- _posts/linux/linux工具系列/linux_tools_cmd.md | 85 +++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 _posts/linux/linux工具系列/linux_tools_cmd.md diff --git a/_posts/linux/linux工具系列/linux_tools_cmd.md b/_posts/linux/linux工具系列/linux_tools_cmd.md new file mode 100644 index 0000000..f983f7b --- /dev/null +++ b/_posts/linux/linux工具系列/linux_tools_cmd.md @@ -0,0 +1,85 @@ +Linux服务端开发工作这5年，我把这些珍藏的linux命令告诉你 + +一般的Linux使用者只需要掌握基础操作命令即可，比如`cd`、`ls`、`rm`等，作为开发人员，如果你想成为一名Linux开发人员，不可避免的需要用到一些更高级的命令，作为后端开发人员，我总结了下面这些开发工作中，使用非常频繁的Linux命令，有了他们相信能帮你事半功倍，工具用的好，下班下的早。 + +## strace + +`strace - trace system calls and signals` + +strace后面跟着启动一个进程，你可以跟踪启动后进程的系统调用和信号，有了这个命令可以看到进程执行时候都调用了哪些系统调用，通过指定不同的选项可以输出系统调用发生的时间，精度可以精确到微秒，甚至还可以统计分析系统调用的耗时，这个用法排查问题的时候很有用，能帮你发现进程卡在哪个系统调用上。已经在运行的进程也可以指定`-p`参数加`pid`像`gdb attach`那样附着上去跟踪。 + +> 什么是系统调用？**系统调用**（英语：system call），指运行在用户空间]的程序向[操作系统内核请求需要更高权限运行的服务。系统调用提供用户程序与操作系统之间的接口。 + +```shell +$strace ./time_test +access("/usr/local/sa/agent/log/execOn", F_OK) = 0 +readlink("/proc/3768/exe", "/usr/bin/strace", 2047) = 15 +getuid() = 560 +getppid() = 3767 +open("/proc/3767/cmdline", O_RDONLY) = 3 +fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 +mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f78d088b000 +read(3, "strace\0./time_test\0", 9216) = 19 +read(3, "", 9216) = 0 +close(3) = 0 +munmap(0x7f78d088b000, 4096) = 0 +getcwd("/data/linlongchen/test", 511) = 23 +ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0 +readlink("/proc/self/fd/0", "/dev/pts/92", 4095) = 11 +socket(PF_FILE, SOCK_DGRAM, 0) = 3 +fcntl(3, F_GETFL) = 0x2 (flags O_RDWR) +fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 +fcntl(3, F_GETFD) = 0 +fcntl(3, F_SETFD, FD_CLOEXEC) = 0 +sendto(3, "\0\0\0\4\0\0\0\266\0\v./time_test\0\16./time_te"..., 182, 0, {sa_family=AF_FILE, path="/usr/local/sa/agent/log/agent_cmd.sock"}, 40) = 182 +close(3) = 0 +execve("./time_test", ["./time_test"], [/* 30 vars */]) = 0 +brk(0) = 0xe31000 +mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5a3ac9a000 +access("/etc/ld.so.preload", R_OK) = 0 +open("/etc/ld.so.preload", O_RDONLY) = 3 +fstat(3, {st_mode=S_IFREG|0644, st_size=18, ...}) = 0 +mmap(NULL, 18, PROT_READ|PROT_WRITE, MAP_PRIVATE, 3, 0) = 0x7f5a3ac99000 +close(3) = 0 +readlink("/proc/self/exe", "/data/linlongchen/test/time_test", 4096) = 32 +``` + +``` +$strace -c ./time_test +time: 2020-03-26 20:20:17 +% time seconds usecs/call calls errors syscall +------ ----------- ----------- --------- --------- ---------------- + -nan 0.000000 0 10 read + -nan 0.000000 0 1 write + -nan 0.000000 0 42 32 open + -nan 0.000000 0 11 close + -nan 0.000000 0 12 12 stat + -nan 0.000000 0 12 fstat + -nan 0.000000 0 1 lseek + -nan 0.000000 0 26 mmap + -nan 0.000000 0 11 mprotect + -nan 0.000000 0 4 munmap + -nan 0.000000 0 3 brk + -nan 0.000000 0 1 ioctl + -nan 0.000000 0 2 access + -nan 0.000000 0 1 socket + -nan 0.000000 0 1 sendto + -nan 0.000000 0 1 execve + -nan 0.000000 0 4 fcntl + -nan 0.000000 0 1 getcwd + -nan 0.000000 0 3 readlink + -nan 0.000000 0 1 getuid + -nan 0.000000 0 1 getppid + -nan 0.000000 0 1 arch_prctl +------ ----------- ----------- --------- --------- ---------------- + +``` + + + +## pstack + +`print a stack trace of a running process` + + +