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Top Forums Shell Programming and Scripting Perl, searching multiple files and printing returned line to new file Post 302448005 by Yogesh Sawant on Wednesday 25th of August 2010 04:03:10 AM
Old 08-25-2010
are you still invoking grep command from your perl script? if yes, use the m operator of Perl instead.
here's a plan that could work for you:
1. get a list of all *.txt files, using opendir and readdir
2. open multiple threads
3. in each thread, open a single file from the list and search the string using m operator, append the results in the output file

but this approach would work only if i/o sub-system is fast in your system. otherwise cpu and memory would wait for io if disks are slower.
 

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opendir(3C)						   Standard C Library Functions 					       opendir(3C)

NAME
opendir, fdopendir - open directory SYNOPSIS
#include <sys/types.h> #include <dirent.h> DIR *opendir(const char *dirname); DIR *fdopendir(int fildes); DESCRIPTION
The opendir() function opens a directory stream corresponding to the directory named by the dirname argument. The fdopendir() function opens a directory stream for the directory file descriptor fildes. The directory file descriptor should not be used or closed following a successful function call, as this might cause undefined results from future operations on the directory stream obtained from the call. Use closedir(3C) to close a directory stream. The directory stream is positioned at the first entry. If the type DIR is implemented using a file descriptor, applications will only be able to open up to a total of {OPEN_MAX} files and directories. A successful call to any of the exec functions will close any directory streams that are open in the calling process. See exec(2). RETURN VALUES
Upon successful completion, opendir() and fdopendir() return a pointer to an object of type DIR. Otherwise, a null pointer is returned and errno is set to indicate the error. ERRORS
The opendir() function will fail if: EACCES Search permission is denied for the component of the path prefix of dirname or read permission is denied for dirname. ELOOP Too many symbolic links were encountered in resolving path. ENAMETOOLONG The length of the dirname argument exceeds {PATH_MAX}, or a path name component is longer than {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect. ENOENT A component of dirname does not name an existing directory or dirname is an empty string. ENOTDIR A component of dirname is not a directory. The fdopendir() function will fail if: ENOTDIR The file descriptor fildes does not reference a directory. The opendir() function may fail if: EMFILE There are {OPEN_MAX} file descriptors currently open in the calling process. ENAMETOOLONG Pathname resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX. ENFILE Too many files are currently open on the system. USAGE
The opendir() and fdopendir() functions should be used in conjunction with readdir(3C), closedir(3C) and rewinddir(3C) to examine the con- tents of the directory (see the EXAMPLES section in readdir(3C)). This method is recommended for portability. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |opendir() is Standard; | | |fdopendir() is Evolving | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
lstat(2), symlink(2), closedir(3C), readdir(3C), rewinddir(3C), scandir(3C), attributes(5) SunOS 5.11 26 Jun 2007 opendir(3C)
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