File.pm - interface to
file system

Further Information 23-Jul-2001

The File module collects together various file related functions, so that any file system dependence is contained in one module rather than occuring throughout the application.

Routine	Function
File::Do( $string )	Conditional file manipulation
File::Find( $root, $name, $opt, $act )	Returns list of files matching name, in directory tree below root
File::InDir( $dir )	Returns list of files in $dir
File::lc( $file )	Returns number of lines in $file
File::Name( @path )	Returns a file name from array @path
File::Tmp( $name, @lines )	Creates temporary file $name, containing the data in @lines
File::Dir_nm( $file )	Returns ( $path, $filename ) for $file
File::sed( $old, $new, $str1, $str2 )	Copies $old to $new, substituting $str2 for $str1

Examples

This example is the test routine File::Test 

sub File::Test{
#... Test File routines 
#
my $tdir = "FileTest" ;
File::Do( "-d $tdir ? cd $tdir ; W : mkdir -v $tdir ; cd $tdir ; pwd " );
#
my( @tmptxt ) = ( "This is a ", "Temporary File " );
File::Tmp( "test.dat", @tmptxt );
File::Do( "-f test.dat ? mv -v test.dat temp.dat : W " );
#
File::Do( "chdir .." );
my( @files ) = File::Find( "./", "*.dat","", "-ls" );
#
my $file ; foreach $file ( @files ) {
print "\n".Err::I( "Found $file" ); }
#
my $Tmp = File::Name( $tdir, "temp.dat" );
File::Do( "-f $Tmp ? rm -v $Tmp : E " );
#
File::Do( "-d $tdir ? rmdir -v $tdir "); 
#
}

Notes

File::Do( $string )

File::Do allows commonly recurring command sequences to be replaced by conditional commands - eg

File::Do( "-f test.dat ? mv -v test.dat temp.dat : W " );

replaces the command sequence

if( -f "test.dat" ) {
	`mv -v test.dat temp.dat` }
else {
	print "\n".Err::W( "test.dat does not exist " ) }

File::Do also formats the command verification messages ( activated by the switch -v ) , inserting line breaks between file names.

Four standard tests are recognised  -  -f , -d , -l, -e  for files, directories, links, or any file system object. 

It is not necessary to use the conditional construction ; 

File::Do( "mv -v test.dat temp.dat " ) 

is also acceptable. 

Commands

The characters  I, W, E, F  cause information, warning, error or fatal messages to be printed. File::Do returns with status 0, 1, 2, 3 for I,W,E,F. The messages are identified with the name of the routine which calls Do . 

If a number is given as a conditional command, then Do will return the number - eg

File::Do( -f $file ? 8 : 12 ) 

returns 8 if $file exists, otherwise 12. 

cd, chdir

invoke the Perl chdir function

mkdir, rmdir 

execute the corresponding unix commands, but translate the standard verification flag '-v' to the non-standard '--verbose' required by these commands ( Redhat 7 now accepts -v as well )

Anything else will be executed ( backticks ) and the output , if any , printed. The two command sections ( before/after : ) may each contain more than one unix command, separated by ; 

File::Find( $root, $name, $opt, $act )

Find is an interface to the find command, returning an array of file names matching $name in the directory tree below $root.

my( @files ) = File::Find( "./", "*.dat","", "-ls" );

The 3rd argument ( which is optional ) may be used to pass additional arguments to find - eg

-maxdepth,1

restricts the search to the root directory & its immediate descendents

-follow

allows directories linked to the tree below root to be searched

For other options , see man find .
The fourth argument allows different actions to be specified, in place of the default ( -print ) . Only -ls appears particularly useful..

File::InDir( $dir )

returns a list of the files in $dir. The up and self links ( /.. , /. ) are excluded.