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如果你只想知道命令位置

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如果你只想知道命令位置

我正在寻找一种可靠的方法来找出我输入命令时运行的程序在文件系统中的位置。

ps -ef给我所有当前正在运行的进程的列表（-e表示每个；-f表示带有相关参数的完整列表）。

因此，为了找到程序的位置uname，我尝试

grep `uname -n &` `ps -ef`

我正在尝试捕获uname -n的进程 ID (PID) 并将其转发给grep，它应该返回包含该 PID 的行，这样我就可以看到当前正在运行哪个命令。

我知道有像tee、管道这样的命令……但我还没有成功地将它们结合起来来实现我的目标。

我假设有一些 shell 函数返回被调用函数的标准输出，类似于：

stdout(some__command)

所以我可以打电话：

grep stdout(uname -n &)  stdout(ps -ef).

我在这里遗漏了什么？

答案1

如果你只想知道命令位置

如果您想知道顶级命令存储在哪个目录中，您有多种选择：

$ which uname
/bin/uname

$ type -a uname
uname is /bin/uname

$ locate uname
/bin/uname
    (... SNIP dozens of Windows files on C & D ...)
/usr/lib/klibc/bin/uname
/usr/lib/plainbox-provider-resource-generic/bin/uname_resource
/usr/share/man/man1/uname.1.gz
/usr/share/man/man2/oldolduname.2.gz
/usr/share/man/man2/olduname.2.gz
/usr/share/man/man2/uname.2.gz

最后一个选项locate返回所有文件，uname不仅包含从命令提示符运行的程序。

strace——跟踪系统调用和中断

您不需要pid通过调用的命令列表来查找函数调用的各种命令的名称。strace所有命令名称都会直接显示。

对于你的uname -n例子，输出是：

$ strace uname -n
execve("/bin/uname", ["uname", "-n"], [/* 62 vars */]) = 0
brk(NULL)                               = 0x2356000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=109073, ...}) = 0
mmap(NULL, 109073, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ff2f9a9f000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff2f9a9e000
mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7ff2f94cb000
mprotect(0x7ff2f968b000, 2097152, PROT_NONE) = 0
mmap(0x7ff2f988b000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7ff2f988b000
mmap(0x7ff2f9891000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7ff2f9891000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff2f9a9d000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff2f9a9c000
arch_prctl(ARCH_SET_FS, 0x7ff2f9a9d700) = 0
mprotect(0x7ff2f988b000, 16384, PROT_READ) = 0
mprotect(0x606000, 4096, PROT_READ)     = 0
mprotect(0x7ff2f9aba000, 4096, PROT_READ) = 0
munmap(0x7ff2f9a9f000, 109073)          = 0
brk(NULL)                               = 0x2356000
brk(0x2377000)                          = 0x2377000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=10219008, ...}) = 0
mmap(NULL, 10219008, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ff2f8b0c000
close(3)                                = 0
uname({sysname="Linux", nodename="alien", ...}) = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 2), ...}) = 0
write(1, "alien\n", 6alien
)                  = 6
close(1)                                = 0
close(2)                                = 0
exit_group(0)                           = ?
+++ exited with 0 +++

更多信息请参阅man strace：

STRACE(1)                           General Commands Manual                           STRACE(1)

NAME
       strace - trace system calls and signals

SYNOPSIS
       strace  [-CdffhikqrtttTvVxxy]  [-In] [-bexecve] [-eexpr]...  [-acolumn] [-ofile] [-sstr‐
       size] [-Ppath]... -ppid... / [-D] [-Evar[=val]]... [-uusername] command [args]

       strace -c[df] [-In] [-bexecve] [-eexpr]...   [-Ooverhead]  [-Ssortby]  -ppid...  /  [-D]
       [-Evar[=val]]... [-uusername] command [args]

DESCRIPTION
       In  the  simplest  case strace runs the specified command until it exits.  It intercepts
       and records the system calls which are called by a process and  the  signals  which  are
       received by a process.  The name of each system call, its arguments and its return value
       are printed on standard error or to the file specified with the -o option.

       strace is a useful diagnostic, instructional, and debugging  tool.   System  administra‐
       tors,  diagnosticians  and trouble-shooters will find it invaluable for solving problems
       with programs for which the source is not readily available since they do not need to be
       recompiled  in  order to trace them.  Students, hackers and the overly-curious will find
       that a great deal can be learned about a system and its system  calls  by  tracing  even
       ordinary  programs.   And  programmers will find that since system calls and signals are
       events that happen at the user/kernel interface, a close examination of this boundary is
       very  useful  for  bug  isolation, sanity checking and attempting to capture race condi‐
       tions.

以上只是手册页的开头strace

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