ids2ngram(1) [debian man page]
IDS2NGRAM(1) User Contributed Perl Documentation IDS2NGRAM(1) NAME
ids2ngram - generate n-gram data file from ids file SYNOPSIS
ids2ngram [option]... ids_file... DESCRIPTION
ids2ngram generates idngram file, which is a sorted [id1,..,idN,freq] array, from binary id stream files. Here, the id stream files are always generated by mmseg or slmseg. Basically, it finds all occurrence of n-words tuples (i.e. the tuple of (id1,..,idN)), and sorts these tuples by the lexicographic order of the ids make up the tuples, then write them to specified output file. INPUT
The input file is presented as a binary id stream, which looks like: [id0,...,idX] OPTIONS
All the following options are mandatory. -n,--NMax N Generates N-gram result. ids2ngram does only support uni-gram, bi-gram, and trigram, so any number not in the range of 1..3 is not valid. -s,--swap swap-file Specify the temporary intermediate file. -o, --out output-file Specify the result idngram file, e.g. the array of [id1, ..., idN, freq] -p, --para N Specify the maximum n-gram items per paragraph. ids2ngram writes to the temporary file on a per-paragraph basis. Every time it writes a paragraph out, it frees the corresponding memory allocated for it. When your computer system permits, a higher N is suggested. This can speed up the processing speed because of less I/O. EXAMPLE
Following example will use three input idstream file idsfile[1,2,3] to generate the idngram file all.id3gram. Each para (internal map size or hash size) would be 1024000, using swap file for temp result. All temp para result would eventually be merged to got the final result. ids2ngram -n 3 -s /tmp/swap -o all.id3gram -p 1024000 idsfile1 idsfile2 idsfile3 AUTHOR
Originally written by Phill.Zhang <phill.zhang@sun.com>. Currently maintained by Kov.Chai <tchaikov@gmail.com>. SEE ALSO
mmseg(1), slmseg(1), slmbuild (1). perl v5.14.2 2012-06-09 IDS2NGRAM(1)
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tmpfs(7FS) File Systems tmpfs(7FS) NAME
tmpfs - memory based file system SYNOPSIS
#include <sys/mount.h> mount (special, directory, MS_DATA, "tmpfs", NULL, 0); DESCRIPTION
tmpfs is a memory based file system which uses kernel resources relating to the VM system and page cache as a file system. Once mounted, a tmpfs file system provides standard file operations and semantics. tmpfs is so named because files and directories are not preserved across reboot or unmounts, all files residing on a tmpfs file system that is unmounted will be lost. tmpfs file systems can be mounted with the command: mount -F tmpfs swap directory Alternatively, to mount a tmpfs file system on /tmp at multi-user startup time (maximizing possible performance improvements), add the following line to /etc/vfstab: swap -/tmp tmpfs - yes - tmpfs is designed as a performance enhancement which is achieved by caching the writes to files residing on a tmpfs file system. Perfor- mance improvements are most noticeable when a large number of short lived files are written and accessed on a tmpfs file system. Large com- pilations with tmpfs mounted on /tmp are a good example of this. Users of tmpfs should be aware of some constraints involved in mounting a tmpfs file system. The resources used by tmpfs are the same as those used when commands are executed (for example, swap space allocation). This means that large sized tmpfs files can affect the amount of space left over for programs to execute. Likewise, programs requiring large amounts of memory use up the space available to tmpfs. Users running into this constraint (for example, running out of space on tmpfs) can allocate more swap space by using the swap(1M) command. Another constraint is that the number of files available in a tmpfs file system is calculated based on the physical memory of the machine and not the size of the swap device/partition. If you have too many files, tmpfs will print a warning message and you will be unable to create new files. You cannot increase this limit by adding swap space. Normal file system writes are scheduled to be written to a permanent storage medium along with all control information associated with the file (for example, modification time, file permissions). tmpfs control information resides only in memory and never needs to be written to permanent storage. File data remains in core until memory demands are sufficient to cause pages associated with tmpfs to be reused at which time they are copied out to swap. An additional mount option can be specified to control the size of an individual tmpfs file system. SEE ALSO
df(1M), mount(1M), mount_tmpfs(1M), swap(1M), mmap(2), mount(2), umount(2), vfstab(4) System Administration Guide: Basic Administration DIAGNOSTICS
If tmpfs runs out of space, one of the following messages will display in the console. directory: File system full, swap space limit exceeded This message appears because a page could not be allocated while writing to a file. This can occur if tmpfs is attempting to write more than it is allowed, or if currently executing programs are using a lot of memory. To make more space available, remove unnecessary files, exit from some programs, or allocate more swap space using swap(1M). directory: File system full, memory allocation failed tmpfs ran out of physical memory while attempting to create a new file or directory. Remove unnecessary files or directories or install more physical memory. WARNINGS
Files and directories on a tmpfs file system are not preserved across reboots or unmounts. Command scripts or programs which count on this will not work as expected. NOTES
Compilers do not necessarily use /tmp to write intermediate files therefore missing some significant performance benefits. This can be remedied by setting the environment variable TMPDIR to /tmp. Compilers use the value in this environment variable as the name of the direc- tory to store intermediate files. swap to a tmpfs file is not supported. df(1M) output is of limited accuracy since a tmpfs file system size is not static and the space available to tmpfs is dependent on the swap space demands of the entire system. SunOS 5.11 9 Oct 1990 tmpfs(7FS)