user-0 提问: 为什么有的打印了，有的没有打印？

回复:
user: user-0
content: 引用 5 楼 zhao4zhong1 的回复:在每个不带末尾\n的fprintf(stderr,"...");后面加 fflush(stderr);  不是这个原因，我加了fflush，试了下，还是没有。

user: user-1
content: 在每个不带末尾\n的fprintf(stderr,"...");后面加 fflush(stderr);

user: user-0
content: 引用 2 楼 xiaohuh421 的回复:1. 打印到文件的同时打印到控制止台, 确认代码 执行到. 2. 文件是否正常关闭,或者刷新, 因为输出文件是有缓存的, 只有当一定条件, 这些数据才会真正写入到文件中.  比如缓冲区满, 主动刷新, 或者文件被关闭. 对于1，我确实是这样做的，已经确认代码执行到。 对于2，我是这样执行的， test  2>temp.txt  ，错误重定向，应该不会是文件缓冲区的问题吧，我上面已经给出了代码了。

user: user-0
content: 引用 1 楼 a30037338 的回复:贴代码。。。。。。  代码太长，没法贴，贴其他地方了。请搜索一下  aaaaa  bbbbb,2个打印的地方  http://blog.sina.com.cn/s/blog_55ff379d0102vuch.html

user: user-2
content: 1. 打印到文件的同时打印到控制止台, 确认代码 执行到. 2. 文件是否正常关闭,或者刷新, 因为输出文件是有缓存的, 只有当一定条件, 这些数据才会真正写入到文件中.  比如缓冲区满, 主动刷新, 或者文件被关闭.

user: user-1
content: 后台的意思可能就是将所有输出重定向的意思，我猜。 FREOPEN Section: POSIX Programmer's Manual (P) Updated: 2003  --------------------------------------------------------------------------------    NAME freopen - open a stream    SYNOPSIS #include <stdio.h>    FILE *freopen(const char *restrict filename, const char *restrict mode,         FILE *restrict stream);      DESCRIPTION The freopen() function shall first attempt to flush the stream and close any file descriptor associated with stream. Failure to flush or close the file descriptor successfully shall be ignored. The error and end-of-file indicators for the stream shall be cleared.   The freopen() function shall open the file whose pathname is the string pointed to by filename and associate the stream pointed to by stream with it. The mode argument shall be used just as in fopen().   The original stream shall be closed regardless of whether the subsequent open succeeds.   If filename is a null pointer, the freopen() function shall attempt to change the mode of the stream to that specified by mode, as if the name of the file currently associated with the stream had been used. It is implementation-defined which changes of mode are permitted (if any), and under what circumstances.   After a successful call to the freopen() function, the orientation of the stream shall be cleared,  the encoding rule shall be cleared, and the associated mbstate_t object shall be set to describe an initial conversion state.   The largest value that can be represented correctly in an object of type off_t shall be established as the offset maximum in the open file description.     RETURN VALUE Upon successful completion, freopen() shall return the value of stream. Otherwise, a null pointer shall be returned,  and errno shall be set to indicate the error.     ERRORS The freopen() function shall fail if:   EACCES  Search permission is denied on a component of the path prefix, or the file exists and the permissions specified by mode are denied, or the file does not exist and write permission is denied for the parent directory of the file to be created.  EINTR  A signal was caught during freopen().  EISDIR  The named file is a directory and mode requires write access.  ELOOP  A loop exists in symbolic links encountered during resolution of the path argument.  EMFILE  {OPEN_MAX} file descriptors are currently open in the calling process.  ENAMETOOLONG  The length of the filename argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.   ENFILE  The maximum allowable number of files is currently open in the system.  ENOENT  A component of filename does not name an existing file or filename is an empty string.  ENOSPC  The directory or file system that would contain the new file cannot be expanded, the file does not exist, and it was to be created.  ENOTDIR  A component of the path prefix is not a directory.  ENXIO  The named file is a character special or block special file, and the device associated with this special file does not exist.  EOVERFLOW  The named file is a regular file and the size of the file cannot be represented correctly in an object of type off_t.  EROFS  The named file resides on a read-only file system and mode requires write access.   The freopen() function may fail if:   EINVAL  The value of the mode argument is not valid.  ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.  ENAMETOOLONG  Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.   ENOMEM  Insufficient storage space is available.  ENXIO  A request was made of a nonexistent device, or the request was outside the capabilities of the device.  ETXTBSY  The file is a pure procedure (shared text) file that is being executed and mode requires write access.   The following sections are informative.     EXAMPLES    Directing Standard Output to a File The following example logs all standard output to the /tmp/logfile file.     #include <stdio.h> ... FILE *fp; ... fp = freopen ("/tmp/logfile", "a+", stdout); ...      APPLICATION USAGE The freopen() function is typically used to attach the preopened streams associated with stdin, stdout, and stderr to other files.     RATIONALE None.     FUTURE DIRECTIONS None.     SEE ALSO fclose() , fopen() , fdopen() , mbsinit() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>     COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .  --------------------------------------------------------------------------------  Example  /* FREOPEN.C: This program reassigns stderr to the file  * named FREOPEN.OUT and writes a line to that file.  */  #include <stdio.h> #include <stdlib.h>  FILE *stream;  void main( void ) {    /* Reassign "stderr" to "freopen.out": */    stream = freopen( "freopen.out", "w", stderr );     if( stream == NULL )       fprintf( stdout, "error on freopen\n" );    else    {       fprintf( stream, "This will go to the file 'freopen.out'\n" );       fprintf( stdout, "successfully reassigned\n" );       fclose( stream );    }    system( "type freopen.out" ); }   Output  successfully reassigned This will go to the file 'freopen.out'

user: user-0
content: [user@localhost magent]$ sudo lsof |grep magent lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs       Output information may be incomplete.  test    44058                 user    0u      CHR                1,3       0t0       5701 /dev/null test    44058                 user    1u      CHR                1,3       0t0       5701 /dev/null test    44058                 user    2u      CHR                1,3       0t0       5701 /dev/null 这是什么情况？表明重定向了？错误被扔掉了？我不想错误被扔掉，想错误打印出来，如何修改？我都没有看懂程序怎么突然被重定向了，哪位看下我上面链接的代码，告诉我下为什么会被重定向的。

user: user-0
content: 引用 5 楼 zhao4zhong1 的回复:在每个不带末尾\n的fprintf(stderr,"...");后面加 fflush(stderr);  我看了下，这个进程的父进程为1，这是个后台进程，应该和这个有关系，谁能解释下么？

user: user-3
content: 贴代码。。。。。。