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Full Discussion: Is `mv dir dir2` atomic ?
Top Forums UNIX for Dummies Questions & Answers Is `mv dir dir2` atomic ? Post 302170830 by Perderabo on Tuesday 26th of February 2008 10:42:52 PM
Old 02-26-2008
I'm really only familiar with the HP-UX version, but I'm guessing that Linux version must be similar. HP's mvdir is confined to operating in a filesystem...never between filesystems. To understand it, consider the first unix implemention of it... If you have /parent/A which has a lot of files in it and you move it to /parent/B, the original version would invoke the link system call and link A to B. At this point, both A and B exist and they are just two names to the same directory. Then, as soon as possible, it would unlink A. This would leave just B. The operation took two very quick system calls. This was NOT atomic. Between the system calls, the filesystem was in an illegal state. A and B should not be links to the same directory even for a millisecond. Today, instead of two system calls, we use just one...and rename(). This is absolutely atomic. For all intents and purposes A just morphs into B. A and B must be in the same filesystem, but not necessarily have the same exact parent as I have indicated here.
 

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nfexpire(1)															       nfexpire(1)

NAME
nfanon - netflow anonymisation SYNOPSIS
nfanon [options] DESCRIPTION
nfanon is used to anonymise all IP addresses ( src, dst, next hop, router IP etc. ) in the netflow records using the CryptoPAn (Cryptogra- phy-based Prefix-preserving Anonymization) module. The key -K is used to initialize the Rijndael cipher. The key is either a 32 character string, or a 64 hex digit string starting with 0x. See http://www.cc.gatech.edu/computing/Telecomm/cryptopan/ for more information about CryptoPAn. nfanon has several modes of operation. o nfanon reads a sequence of input files, specified by -r, -R and -M and anonymises the flows in the given files. The input file arguments have the same syntax and meaning as nfdump(1). o nfanon reads a sequence of input files, specified by -r, -R and -M. All anonymised flows are written to a single file specified by -w. o nfanon works as filter and reads flows from stding and writes the anonymised flows to stdout. OPTIONS
-r inputfile Read input data from inputfile. Default is read from stdin. -R expr Read input from a sequence of files in the same directory. expr may be one of: /any/dir Read recursively all files in directory dir. /dir/file Read all files beginning with file. /dir/file1:file2 Read all files from file1 to file2. Note: files are read in alphabetical sequence. -M expr Read input from multiple directories. expr looks like: /any/path/to/dir1:dir2:dir3 etc. and will be expanded to the directories: /any/path/to/dir1, /any/path/to/dir2 and /any/path/to/dir3 Any number of colon separated directories may be given. The files to read are specified by -r or -R and are expected to exist in all the given directories. The options -r and -R must not contain any directory part when used in conjunction with -M. -w outputfile If specified writes anonymised netflow records to outputfile. -K key The key is used to initialize the Rijndael cipher. key is either a 32 character string, or a 64 hex digit string starting with 0x. RETURN VALUE
Returns 0 No error. 255 Initialization failed. 250 Internal error. NOTES
None. SEE ALSO
nfdump(1) BUGS
2009-09-09 nfexpire(1)
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