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。


posted @ 2011-09-14 15:46  绿色的麦田  阅读(242)  评论(0编辑  收藏  举报