perl学习（2）文件处理

1、读取某文件，如果该文件不存在，则报错，并提示出错原因

open (DB, "/home/ellie/myfile") or die "Can't open file: $!\n";  

运行后提示：Can't open file: No such file or director

 

2、读写文件的方法：

open(FH, "<filename");     # Opens "filename" for reading.读
                           # The <; symbol is optional.



open(FH, ">filename");     # Opens "filename" for writing.写
                           # Creates or truncates file.



open(FH, ">>filename");     # Opens "filename" for appending.追加
                            # Creates or appends to file.


open(FH, "+<filename");     # Opens "filename" for read, then write.写读后写
open(FH, "+>filename");     # Opens "filename" for write, then read.先写后读


close(FH);                 

 

3、打开并打印该文件

#!/usr/bin/perl

open(FH, "<d:/readtest.txt") or die "Can't open file: $!\n";
while(<FH>){ print }

4、文件属性

#!/usr/bin/perl



my $file="d:/readtest.txt";


# Is it readble, writeable, and executable?
print "File is readable, writeable, and executable\n" if -r $file and -w _ and -x _;


# When was it last modified?
print "File was last modified ",-M $file, " days ago.\n";


#若为目录则打印
print "File is a directory.\n " if -d $file; # Is it a directory?

由于此文件实际存在，并且是刚建不久，但只是普通的文本文件，因此最后的结果为

File was last modified 0.0239930555555556 days ago.     

 

若代码：print "File is readable, writeable, and executable\n" if -r $file and -w _ and -x _;

改为：print "File is readable, writeable, and executable\n" if -r $file and -w _ ;

最后的结果则为：

File is readable, writeable, and executable
File was last modified 0.0251851851851852 days ago.

-w _为-w $file的简写。