I have a Perl script that outputs text. I want to import this text into vim, edit it, save it and then exit. On exit, I want the original Perl script to process the edited file.
E.G. how crontab -e works when you add a new job.
Thanks :)
Sounds like a very plain case to use system to run vim on the filename. That will wait until vim is done, at which point you can go ahead and read the file's new contents.
use File::Temp;
my $fh = new File::Temp();
my $fname = $fh->filename;
print $fh "My Text";
$fh->close();
system($ENV{EDITOR}, $fname);
open $fh, '<', $fname or die "Can't open temp file: $!";
while(<$fh>) { print }
close $fh;
A suggestion: Why don't you grab the source to crontab and see what it does?
Other than that, unwind has your answer.
And I think the way to think about this is:
"Okay, I need a program to write out a file, call vim, then do further processing on the file. So, here's my routine to write the file, here's my routine that calls vim (using system), and here's my routine to do the postprocessing after vim is done. Now I'll lace them all together in my main program, and I'm done!"
You seem to want to pipe the output of your script into vim:
script | vim
And then you want the script to somehow know that Vim is finished and resume. That's not how I/O redirection works. The script has no knowledge of what program its output is being piped into.
You mentioned other programs like crontab and cvs; one thing those have in common is that they invoke the editor themselves. They create temporary files, read the EDITOR or VISUAL environment variables (check the manual for details about how they choose which one), run the given program, and wait for the program to finish. Then they continue running and use the file they specified earlier.
Turns out I've done exactly that in Perl. I created a temporary file (with tempfile), wrote a bunch of text into it, and then used system to invoke the editor on the file. You don't even have to close the file while you run the editor.
Pipe the output to vim - and don't forget the dash at the end.
script.pl | vim -
This will open vim with the contents of the scripts output. Just save it :w filename and exit :q. This isn't how crontab -e works, but it comes close enough in an easy way.
Edit:
I missed this part (or maybe the question was edited afterward):
On exit, I want the original Perl
script to process the edited file.
This isn't the best way to do this, but going with my original answer, this works (if you save the file as file.txt):
perl -le 'print "1234"' | vim - && perl -pe '' file.txt
Just replace the perl commands with your perl commands and it should work. Like I said, this is not the best answer, but it should work.
Related
I just created a text test.conf file with some information. How can I read it on Perl?
I am new to Perl and I am not sue would will I need to do.
I tried the following:
C:\Perl\Perl_Project>perl
#!/usr/local/bin/perl
open (MYFILE, 'test.conf');
while (<MYFILE>)
{ chomp; print "$_\n"; }
close (MYFILE);
I tried installing Perl on my laptop that has Windows 7 OS, and using command line.
Instead of using command line, write your program in a file (you can use any editor to write your program, I would suggest use Notepad++) and save as myprogram.pl in the same directory where you have your .conf file.
use warnings;
use strict;
open my $fh, "<", "test.conf" or die $!;
while (<$fh>)
{
chomp;
print "$_\n";
}
close $fh;
Now open a command prompt and go to the same path where you have your both file myprogram.pl and test.conf file and execute your program by typing this:
perl myprogram.pl
You can give full path of your input file inside program and can run your program from any path from command prompt by giving full path of your program:
perl path\to\myprogram.pl
Side note: Always use use warnings; and use strict; at the top of your program and to open file always use lexical filehandle with three arguments with error handling.
This is an extended comment more than an answer, as I believe #serenesat has given you everything you need to execute your program.
When you do "command line" Perl, it's typically stuff that is relatively brief or trivial, such as:
perl -e "print 2 ** 16"
Anything that goes beyond a few lines, and you're probably better off putting that in a file and having Perl run the file. You certainly can put larger programs on the command line, but when it comes to going back in and editing lines, it becomes more of a hassle than a shortcut.
Also, for what it's worth the -n and -p parameters allow you to process the contents of a stream, meaning you could do something like this:
perl -ne "print if /oracle/i" test.conf
context: I'm a beginner in Perl and struggling, please be patient, thanks.
the question: there is a one-liner that seems to do the job I want (in a cygwin console it does fine on my test file). So now I would need to turn it into a script, but I can't manage that unfortunately.
The one-liner in question is provided in the answer by Aki here Delete lines in perl
perl -ne 'print unless /HELLO/../GOODBYE/' <file_name>
Namely I would like to have a script that opens my file "test.dat" and removes the lines between some strings HELLO and GOODBYE. Here is what I tried and which fails (the path is fine for cygwin):
#!/bin/perl
use strict;
use warnings;
open (THEFILE, "+<test.dat") || die "error opening";
my $line;
while ($line =<THEFILE>){
next if /hello/../goodbye/;
print THEFILE $line;
}
close (THEFILE);
Many thanks in advance!
Your one-liner is equivalent to the following
while (<>) {
print unless /HELLO/../GOODBYE/;
}
Your code does something quite different. You should not attempt to read and write to the same file handle, that usually does not do what you think. When you want to quickly edit a file, you can use the -i "in-place edit" switch:
perl -ni -e 'print unless /HELLO/../GOODBYE/' file
Do note that changes to the file are irreversible, so you should make backups. You can use the backup option for that switch, e.g. -i.bak, but be aware that it is not flawless, as running the same command twice will still overwrite your backup (by saving to the same file name twice).
The simplest and safest way to do it, IMO, is to simply use shell redirection
perl script.pl file.txt > newfile.txt
While using the script file I showed at the top.
I have a Perl script which I want to run every 4 hours through cron. But somehow it fails to execute through cron and runs fine if I run it through command line. Following is the command which I set in crontab:
perl -q /path_to_script/script.pl > /dev/null
Also, when I run this command on command prompt, it does not execute but when I go in the leaf folder in path_to_script and execute the file, it runs fine.
Also, where will the log files of this cron job be created so that I can view them?
You should probably change the working directory to "leaf folder".
Try this in your crontab command:
cd /path_to_script; perl script.pl >/dev/null
Wrt. log files. Cron will mail you the output. But since you sent stdout to /dev/null, only stderr will be mailed to you.
If you want the output saved in a log file, then pipe the stderr/stdout output of the script into a file, like so:
cd /path_to_script; perl script.pl 2>&1 >my_log_file
Usually cron will send you mail with the output of your program. When you're figuring it out, you probably want to check the environment. It won't necessarily be the same environment as your login shell (since it's not a login shell):
foreach my $key ( keys %ENV ) {
printf "$key: $$ENV{$key}\n";
}
If you're missing something you need, set it in your crontab:
SOME_VAR=some_value
HOME=/Users/Buster
If you need to start in a particular directory, you should chdir there. The starting directory from a cron job probably isn't what you think it is. Without an argument, chdir changes to your home directory. However, sometimes those environment variables might not be set in your cron session, so it's probably better to have a default value:
chdir( $ENV{HOME} || '/Users/Buster' );
At various critical points, you should give error output. This is a good thing even in non-cron programs:
open my $fh, '<', $some_file or die "Didn't find the file I was expecting: $!";
If you redirect things to /dev/null, you lose all that information that might help you solve the problem.
looks like you may have missed the
#!/usr/bin/perl
at the start of your perl script which is why you might need perl -q to run it
once you have added that line you can run it directly from the command line using
/path_to_script/script.pl
If you use a command in your perl program, i advise you to put the full path to the command in your program.
I have try to load environment but it is not more helpful.
After a oversee with one colleague, i think it's from interaction between perl and the system environment.
Best regards,
Moustapha Kourouma
As I am still new to Unix and Perl, I'm finding a simple and direct method to grab the Unix command that I had run using Perl script.
What I know is "history" can track back the commands that I had run, but it is not working in Perl using back ticks history to run it.
I tried to put "history > filename" in vi text editor in a temporary file, use command "source" it, and it works, but command "source" also not working in Perl script using back ticks.
Can anyone guide me about my problems? direct me to correct method to solve my problems? T.T
Thanks.
You can't. Shells (well, bash and tcsh, anyway, your shell might, but probably doesn't, vary) only save command history in interactive mode. Commands run in a subshell by a perl script won't be added to the history file.
This will get the history of commands that were run by the user in interactive mode:
$data_file = "~/.bash_history";
open(DAT, $data_file) || die("Could not open file!");
#fileData = <DAT>;
close(DAT);
foreach $command (#fileData) {
# Do things here.
}
As mentioned by Wobble, though, this history file will not include commands run from a Perl script - you'll have to have the script append the command to a file when it runs it, thus creating it's own history file (or, append it to ~/.bash_history, which will have it share the history file with interactive shells).
If you have access to the perl script (that is, you can change it), you can simply write each command run in the perl script to a chosen text file:
sub run_program
{
my $program = shift;
open PROGS, ">>my-commands.txt", or die $!;
print PROGS $program."\n";
`$program`;
close(PROGS);
}
then just run `run_program($command) every time you wish to run a command in the script.
I have a folder full of script files. When I run them, a program to which they are native is opened, it does some stuff and a CSV file is generated. I wrote some code that I want to run each script file and produce a bunch of CSV files, one for each script.
What happens is the following: when my Perl application is executed, the software is launched and the first of the scripts is run successfully (a CSV file is created). However, at this step the Perl application waits for me to close the software before I continue. It does this for every script. What can I do to avoid this from happening?
use strict;
use warnings;
use Cwd;
my $dir = cwd();
opendir(DIR, $dir);
my #files= grep(/\.acs$/,readdir(DIR));
$dir=~s/\//\\/g;
chdir $dir;
foreach (#files)
{
print "$_\n";
system ("$_")
}
I think you'll want to fork and exec and waitpid - i.e. set up and run your own process and wait for it to finish on your own.
http://larc.ee.nthu.edu.tw/~cthuang/courses/ee2320/12_process.html
This isn't easy, but unfortunately, you're doing this on an OS that isn't script-friendly. Doing this under Linux or OS X you wouldn't have any troubles like this.
You'll need to figure out if these commands are even available under Windows. You may have to find some similar things that are available under windows if there is no posix compatibility library.
your best choice is to ask the application nicely to close itself after it is done.
for example, the cmd.exe command have parameter /C that does exactly that.
try to run the application with /?, and see if anything useful comes up.
failing that, you can use Win32::Process to create the process and then kill it after you are sure it is done. see the documentation for that.