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Full Discussion: Creating a file / /dev/null
Top Forums UNIX for Dummies Questions & Answers Creating a file / /dev/null Post 41800 by 435 Gavea on Tuesday 14th of October 2003 11:12:50 PM
Old 10-15-2003
Question Creating a file / /dev/null

First of all, hello there cOmMuNity ! Smilie

Well, I've got two basic questions:

1) In how many ways it's possible to create a file ?
I know one manner using "touch", other typing something like echo "" > file ...
The fact is that I need to overwrite the file if it exists, and touch isn't capable of doing this (actually, touch isn't that suitable for creating files, is it ? as it's destined to change the access date and time of a file...). So, is the echo "" > file the most elegant way for this purpose ?


2) What is exactly the /dev/null... It isn't the same thing as a NULL value, is it ?
Suppose I've chosen to create a file by the echo "" > file method.
The file starts with a blank line. To avoid this, I've seen
cat /dev/null > file

Is this again the only way ?
I heard also that I could use the -n option of echo, which removes the newline character...
It would be something like echo -n "" > file
It should work out.

Well, that's all for now.
Thank you anyway !!!

435 Gavea - bRaZiL - tHE HEll iS hERe ! Smilie
 

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STAT(3) 								 1								   STAT(3)

stat - Gives information about a file

SYNOPSIS
array stat (string $filename) DESCRIPTION
Gathers the statistics of the file named by $filename. If $filename is a symbolic link, statistics are from the file itself, not the sym- link. lstat(3) is identical to stat(3) except it would instead be based off the symlinks status. PARAMETERS
o $filename - Path to the file. RETURN VALUES
stat(3) and fstat(3) result format +--------+--------------------------------------+---+ |Numeric | | | | | | | | | Associative | | | | | | | | Description | | | | | | +--------+--------------------------------------+---+ | 0 | | | | | | | | | dev | | | | | | | | device number | | | | | | | 1 | | | | | | | | | ino | | | | | | | | inode number * | | | | | | | 2 | | | | | | | | | mode | | | | | | | | inode protection mode | | | | | | | 3 | | | | | | | | | nlink | | | | | | | | number of links | | | | | | | 4 | | | | | | | | | uid | | | | | | | | userid of owner * | | | | | | | 5 | | | | | | | | | gid | | | | | | | | groupid of owner * | | | | | | | 6 | | | | | | | | | rdev | | | | | | | | device type, if inode device | | | | | | | 7 | | | | | | | | | size | | | | | | | | size in bytes | | | | | | | 8 | | | | | | | | | atime | | | | | | | | time of last access (Unix timestamp) | | | | | | | 9 | | | | | | | | | mtime | | | | | | | | time of last modification (Unix | | | | timestamp) | | | | | | | 10 | | | | | | | | | ctime | | | | | | | | time of last inode change (Unix | | | | timestamp) | | | | | | | 11 | | | | | | | | | blksize | | | | | | | | blocksize of filesystem IO ** | | | | | | | 12 | | | | | | | | | blocks | | | | | | | | number of 512-byte blocks allocated | | | | ** | | | | | | +--------+--------------------------------------+---+ * On Windows this will always be 0. ** Only valid on systems supporting the st_blksize type - other systems (e.g. Windows) return -1. In case of error, stat(3) returns FALSE. Note Because PHP's integer type is signed and many platforms use 32bit integers, some filesystem functions may return unexpected results for files which are larger than 2GB. ERRORS
/EXCEPTIONS Upon failure, an E_WARNING is emitted. EXAMPLES
Example #1 stat(3) example <?php /* Get file stat */ $stat = stat('C:phpphp.exe'); /* * Print file access time, this is the same * as calling fileatime() */ echo 'Access time: ' . $stat['atime']; /* * Print file modification time, this is the * same as calling filemtime() */ echo 'Modification time: ' . $stat['mtime']; /* Print the device number */ echo 'Device number: ' . $stat['dev']; ?> Example #2 Using stat(3) information together with touch(3) <?php /* Get file stat */ $stat = stat('C:phpphp.exe'); /* Did we failed to get stat information? */ if (!$stat) { echo 'stat() call failed...'; } else { /* * We want the access time to be 1 week * after the current access time. */ $atime = $stat['atime'] + 604800; /* Touch the file */ if (!touch('some_file.txt', time(), $atime)) { echo 'Failed to touch file...'; } else { echo 'touch() returned success...'; } } ?> NOTES
Note Note that time resolution may differ from one file system to another. Note The results of this function are cached. See clearstatcache(3) for more details. Tip As of PHP 5.0.0, this function can also be used with some URL wrappers. Refer to "Supported Protocols and Wrappers" to determine which wrappers support stat(3) family of functionality. SEE ALSO
lstat(3), fstat(3), filemtime(3), filegroup(3). PHP Documentation Group STAT(3)
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