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close(2) [hpux man page]

close(2)							System Calls Manual							  close(2)

close - close a file descriptor SYNOPSIS
closes the file descriptor indicated by fildes. fildes is a file descriptor obtained from a or system call. All associated file segments which have been locked by this process with the function are released (i.e., unlocked). RETURN VALUE
Upon successful completion, returns a value of 0; otherwise, it returns -1 and sets to indicate the error. ERRORS
fails if the any of following conditions are encountered: [EBADF] fildes is not a valid open file descriptor. [EINTR] An attempt to close a slow device or connection or file with pending aio requests was interrupted by a signal. The file descriptor still points to an open device or connection or file. [ENOSPC] Not enough space on the file system. This error can occur when closing a file on an NFS file system. [When a system call is executed on a local file system and if a new buffer needs to be allocated to hold the data, the buffer is mapped onto the disk at that time. A full disk is detected at this time and returns an error. When the system call is executed on an NFS file system, the new buffer is allocated without communicating with the NFS server to see if there is space for the buffer (to improve NFS performance). It is only when the buffer is written to the server (at file close or the buffer is full) that the disk-full condition is detected.] SEE ALSO
creat(2), dup(2), exec(2), fcntl(2), lockf(2), open(2), pipe(2), thread_safety(5). STANDARDS CONFORMANCE

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dup2(2) 							System Calls Manual							   dup2(2)

dup2 - duplicate an open file descriptor to a specific slot SYNOPSIS
fildes is a file descriptor obtained from a or system call. fildes2 is a non-negative integer less than the maximum value allowed for file descriptors. causes fildes2 to refer to the same file as fildes. If fildes2 refers to an already open file, the open file is closed first. The file descriptor returned by has the following in common with fildes: o Same open file (or pipe). o Same file pointer (that is, both file descriptors share one file pointer.) o Same access mode (read, write or read/write). o Same file status flags (see fcntl(2), The new file descriptor is set to remain open across system calls. See fcntl(2). This routine is found in the C library. Programs using but not using other routines from the Berkeley importability library (such as the routines described in bsdproc(3C)) should not give the option to ld(1). RETURN VALUE
Upon successful completion, returns the new file descriptor as a non-negative integer, fildes2. Otherwise, it returns -1 and sets to indi- cate the error. ERRORS
fails if the following is true: fildes is not a valid open file descriptor or fildes2 is not in the range of legal file descriptors. An attempt to close fildes2 was interrupted by a signal. The file is still open. WARNINGS
A multithreaded application or an application with a signal handler can exhibit a race between on one thread and another kernel call that assigns a new file descriptor while running on a second thread or signal handler. If fildes2 is free before the call was made, the other thread or signal handler may win the race and acquire that descriptor (e.g., in an call). The thread calling can then close this file and reuse the descriptor. This results in multiple functions improperly referring to the same file. This race can be avoided either by ensuring that fildes2 references an open file before calling or by providing user-level synchronization (or signal disabling) which makes sure that the thread and another thread or signal handler don't make competing calls into the kernel at the same time. SEE ALSO
close(2), creat(2), dup(2), exec(2), fcntl(2), open(2), pipe(2), privileges(5). STANDARDS CONFORMANCE
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