linux - linux "cp"命令流程图

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我想知道cp怎么办命令被执行。我的意思是它从最顶层到内核然后再返回的流程？它的流量是多少？当我们写 cp 时会发生什么命令以及它是如何发生的？请详细说一下。

Answer 1

foo.c cp之前的内容:

this is foo

strace cp foo.c bar.c 给了我这个:

execve("/bin/cp", ["cp", "foo.c", "bar.c"], [/* 58 vars */]) = 0

//several calls to open, fstat64, mmap2, close

open("foo.c", O_RDONLY|O_LARGEFILE)     = 3
    fstat64(3, {st_mode=S_IFREG|0664, st_size=12, ...}) = 0

    open("bar.c", O_WRONLY|O_CREAT|O_EXCL|O_LARGEFILE, 0664) = 4
        fstat64(4, {st_mode=S_IFREG|0664, st_size=0, ...}) = 0
        read(3, "this is foo\n", 32768)         = 12
        write(4, "this is foo\n", 12)           = 12
        read(3, "", 32768)                      = 0
    close(4)                                = 0
close(3)                                = 0

close(0)                                = 0  // close stdin
close(1)                                = 0  // close stdout
close(2)                                = 0  // close stderr
exit_group(0)                           = ?