I have a perl file (eg:test.pl) which does some DB operations.
While testing, its working fine.
I execute this file as a background process by using the command
perl test.pl &
Its working properly for some days.
But after some days ,the file execution get stopped.
How can I find the reason or view the error?
I checked the log file "/var/log/httpd/error_log", but can't find anything.
I keep the perl file in a server, which runs in Cent OS.
Any one have idea?
There is no 'perl error log'
But you can define a destination for output to be saved to, just run your script like this:
perl test.pl >> /var/log/some-log-file.log 2>&1 &
This will redirect STDOUT (normal shell output) and STDERR (error output) to /var/log/some-log-file.log instead of to the terminal.
You may also wish to use nohup in order to have the script ignore HANGUP (logout) signals, which could be causing your unexpected terminations:
nohup perl test.pl >> /var/log/some-log-file.log 2>&1 &
Obviously, whichever user you run the script as will need to have write access to the log file.
Related
I'm running a script in solaris 11 with different results depending of the shell used.
The script has an echo redirecting to a file given by an environment value:
echo "STARTING EXEC" >> $FILE
ps. EXEC is just the message the script show, it's not using exec command.
If I execute the script without the variable FILE defined (using /usr/bin/ksh):
./start.sh[10]: : cannot open
and the script continue the execution.
The flags for ksh are:
echo $-
imsuBGEl
But if I change to /usr/xpg4/bin/sh, the script show me the echo in stdout and there is no error shown.
The flags for xpg4 sh are:
echo $-
imsu
I tried to change the flags with set +- (I can't remove El flags, but BG are removed ok), but can't get the same behavior.
Is there anything I can do to get the same result using ksh without cannot open error?
/usr/bin/ksh --version
version sh (AT&T Research) 93u 2011-02-08
I'll want the script keep going, showing the message in stdout, instead of showing the error just like it does now.
Like shellter said in the comments, the good thing to do is to check if the FILE variable is defined before doing anything. This is a script migration from an HPUX to a SOLARIS environment, and client think they must have the same result as before (we unset FILE variable before execution to test it).
You are likely running Solaris 11, not Solaris 64.
Should you want to have your scripts to work under Solaris 11 without having to search everywhere the bogus redirections, you can simply replace all shebangs (first line) by #!/usr/xpg4/bin/sh.
The final solution we are going to take is to install the ksh88 package and use it like default shell (/usr/sunos/bin/ksh). This shell have the same behavior the client had before, and we can let the scripts with no modifications.
The ksh used in solaris 11 is the 93 (http://docs.oracle.com/cd/E23824_01/html/E24456/userenv-1.html#shell-1)
Thanks #jlliagre and #shellter for your help.
I'm coding a Perl script to generate images with text in them. I'm on a Linux machine. I'm using pbmtextps. When I try to run pbmtextps in Perl with a system call like this
system("pbmtextps -fontsize 24 SampleText > out.pbm");
I get this error message
pbmtextps: failed to run Ghostscript process: rc=-1
However, if I run the exact same pbmtextps command from the command-line outside of Perl, it runs with no errors.
Why does it cause the ghostscript error when I run it from inside a Perl script?
ADDITIONAL INFO: I tried to hack around this by creating a C code called mypbmtextps.c which does the exact same thing with a C system call. That works from the command line. No errors. But then when I call that C program from the Perl script, I get the same ghostscript error.
ANSWER: I solved it. The problem was this line in the PERL script:
$SIG{CHLD} = 'IGNORE';
When I got rid of that (which I need for other things, but not in this script) it worked okay. If anyone knows why that would cause a problem, please add that explanation.
Ah-ha. Well, the SIGCHLD is required for wait(), and so required for perl to be able to retrieve the exit status of the child process created by system(). In particular, system() always returns -1 when SIGCHLD is ignored. $? will also be unavailable with SIGCHLD blocked.
What printed the error message? pbmtextps, or your perl script?
As far as I know, the signal handler for your perl process shouldn't affect the signal handler for the child processes, but this could depend on your version of perl and your OS version. On my Linux Mint 13 with Perl 5.14.2 the inner perl script prints 0, with the outer script printing -1:
perl -e '$SIG{CHLD}= "IGNORE"; print system(q{perl -e "print system(q(/bin/sleep 1))"})'
Is your perl script modifying the environment?
You can test with
system("env > /tmp/env.perl");
and then compare it to the environment form your shell:
env > /tmp/env.shell
diff /tmp/env.shell /tmp/env.perl
Is the perl script also being run from the shell, or is it being run from some other process like cron or apache? (in particular, you should check $PATH)
I wrote a shell script that I use under ash, and I redirect stderr and stdout to a log file. I would like that log file to be emailed to me only if stderr is not empty.
I tried:
exec >mylog.log 2>&1
# Perform various find commands
if [TEST_IF_STDERR_NOT_EMPTY]; then
/usr/bin/mail -s "mylog" email#mydomain.com < mylog.log
fi
My question is twofold:
1- I get a -sh: /usr/bin/mail: not found error. It seems that the mail command doesn't exist under ash (or at least under my linux box, which is a Synology NAS), what would be the alternative? Worst case, perl is available, but I would prefer to use standard sh commands.
2- How to I test that stderr is not empty?
Thanks
How to check if file is empty in bash
As for the first question, in your code you are calling mail but lower in the post you are calling email. Check your code and make sure it is mail.
Use which mail to get the full path. Maybe it is not installed in /usr/bin/.
Use find to locate mail.
If you can go to another shell, run it and then execute which mail to get the full path of mail in case the path is set up in the alternative shells.
I'm sure this is an easy fix, but I need to use "script" (and not collect standard in/out/error) for my project. I'm somewhat new to Perl, so please bear with me.
I have a Perl script that works fine. When I run it I generally type script > filename before I run Perl.
$script > file.log
bash-3.2$ perl foobar.pl
This runs fine, and when I'm done I type exit or control D to stop the script and save the file. All I'd like to do is incorporate the script command in Perl and then automatically capture the file when the program stops running (12-16 hours). The problem I have is that is I call in system("script > file.log"); and them call system("perl foobar.pl"); it hangs at the bash-3.2$ prompt. The only way to get Perl to work is control D or exit, stopping the script function.
Anyone have any idea how to fix this? While it's easy to start with script before invoking Perl, if I'm a mole and forget, I have to rerun the program (which takes a long time).
Have you considered using system("script -c 'perl foobar.pl' file.log")?
I have a program which reads the output from external application.The external app gives set of output. My program reads the output from this external app while($line=<handle to external app>) and print it to STDOUT.But the "print $line STDOUT" prints only some lines and when the error has occurred ,print to STDOUT is not working , but my one more logging statement "push #arr,$line" has stored complete output from the external app.From this i got to know STDOUT is not working properly when error happens.
Eg:
if external app output is like:
Starting command
First command executed successfully
Error:123 :next command failed
Program terminated
In here the STDOUT prints only :
Starting command
First command executed successfully
But if I check the array it has complete output including error details. So I guessed STDOUT has been redirected or lost.
So I tried storing STDOUT in the beginning of the program to $old_handle using open and then try to restore it before print statement using select($old_handle) (thinking some thing redirects STDOUT when error happens)
But I was not successfull, I don't know what is wrong here. Please help me.
It's possible the output is being buffered. Try setting
$| = 1;
at the start of your program. This will cause the output to be displayed straight away, rather than being buffered for later.
Just guess, may be because error output doesn't go to STDOUT. Use redirect
first_program |& perl_program
or
first_program 2>&1 | perl_program