String replace perl script error

Shell Programming and Scripting
1

I have written down a simple perl program to replace a string from a word file. My script does'nt seem to work. Any pointers to make it work will be appreciated. The code is given below.

#!/usr/bin/perl

while (<>) {
 open(FILE,$_);
 while (<FILE>) {
        s/This/I did it/g;
        }
 close(FILE);
}

I run the script from the command line as:
perl myscript.pl inputfile.txt

2

What is your expected results?

3

This you can do from the command line, from a shell script, or you can put it in a perl script.

$1 is whatever you pass to the script.

Put this command in a file called replace and run it like this
#replace inputfile.txt

This searches the file $1, ($1 is what you pass to the replace script) it looks for the word 'This' and replaces in with 'I did it' and prints it to a new file called /tmp/newinputfile.txt.

perl -e 'while(<>){if(/This/){$="I did it\n"} print "$"}' $1 > /tmp/newiputfile.txt

Hope this helps

-X

4

The file, "input.txt" contains the following string:

This is the text I wrote

To start with, I want to replace the word "This" with "I did it".

5

Here.....This is even better....Since the source file and destination file are the same, consider doing something like this.

commandline
perl -pi -w -e 's/This/I did it/g;' inputfile.txt

script
perl -pi -w -e 's/This/I did it/g;' $1

Run script from commandline.

#myscript.pl inputfile.txt

This is sweet...

-X

6

I noticed that I the file specified on the command line will be read line by line. I modified the script as below but it still does'nt work. Can there be some problem with file permissions?

#!/usr/bin/perl

while (<>) {
         s/This/I did it/g;
     }
7 
#!/usr/bin/perl -i

while (<>) {
        s/This/I\ did\ it/g;
        print;
}

perl -i myscript.pl input.txt