I am running my tests using TAP::Harness , when I run the tests from command line on a Linux system I get the test results on STDOUT as it is run but when i try to capture the output to a file as well as STDOUT using perl harness.pl | tee out.tap the results are buffered and displayed only at the end, I tried passing in a file handle to the new but the results are still buffered before being written to a file , Is there a way not to buffer the output, I have a long running suite and would like to look at the results while the tests are running as well as capture the output.
TAP::Harness version 3.22 and perl version 5.8.8
here is the sample code
harness.pl
#!/usr/bin/perl
use strict;
use warnings;
use TAP::Harness;
$|++;
my #tests = ('del.t',);
my $harness = TAP::Harness->new( {
verbosity => 1,
} );
$harness->runtests(#tests);
and the test del.t
use Test::More qw /no_plan/;
$|++;
my $count =1;
for (1 ..20 ) {
ok ( $count ++ == $_, "Pass $_");
sleep 1 if ( $count % 5 == 0 ) ;
}
Using script instead of tee does what you want:
script -c 'perl harness.pl' file
Found a simple change to make tee work as well: Specify a formatter_class:
my $harness = TAP::Harness->new( {
verbosity => 1,
formatter_class => 'TAP::Formatter::Console',
} );
This is because TAP::Harness normally uses a different default one if the output is not a tty, which is what is causing the buffering you're seeing.
Related
I don't have much experience with perl, and would appreciate any/all feedback....
[Before I start: I do not have access/authority to change the existing perl scripts.]
I run a couple perl scripts several times a day, but I would like to begin capturing their output in a file.
The first perl script does not take any arguments, and I'm able to "tee" its output without issue:
/asdf/loc1/rebuild-stuff.pl 2>&1 | tee $mytmpfile1
The second perl script hangs with this command:
/asdf/loc1/create-site.pl --record=${newsite} 2>&1 | tee $mytmpfile2
FYI, the following command does NOT hang:
/asdf/loc1/create-site.pl --record=${newsite} 2>&1
I'm wondering if /asdf/loc1/create-site.pl is trying to process the | tee $mytmpfile2 as additional command-line arguments? I'm not permitted to share the entire script, but here's the beginning of its main routine:
...
my $fullpath = $0;
$0 =~ s%.*/%%;
# Parse command-line options.
...
Getopt::Long::config ('no_ignore_case','bundling');
GetOptions ('h|help' => \$help,
'n|dry-run|just-print' => \$preview,
'q|quiet|no-mail' => \$quiet,
'r|record=s' => \$record,
'V|noverify' => \$skipverify,
'v|version' => \$version) or exit 1;
...
Does the above code provide any clues? Other than modifying the script, do you have any tips for allowing me to capture its output in a file?
It's not hanging. You are "suffering from buffering". Like most programs, Perl's STDOUT is buffered by default. Like most programs, Perl's STDOUT is flushed by a newline when connected to a terminal, and block buffered otherwise. When STDOUT isn't connected to a terminal, you won't get any output until 4 KiB or 8 KiB of output is accumulated (depending on your version of Perl) or the program exits.
You could add $| = 1; to the script to disable buffering for STDOUT. If your program ends with a true value or exits using exit, you can do that without changing the .pl file. Simply use the following wrapper:
perl -e'
$| = 1;
$0 = shift;
do($0);
my $e = $# || $! || "$0 didn\x27t return a true value\n";
die($e) if $e;
' -- prog args | ...
Or you could fool the program into thinking it's connected to a terminal using unbuffer.
unbuffer prog args | ...
I have given some compiled program. I want to communicate with it from my bash script by program stdin and stdout. I need two way communication. Program cannot be killed between exchange of information. How I can do that?
Simple example:
Let that program be compiled partial summation (C++) and script results will be squares of that sums. Program:
int main() {
int num, sum = 0;
while(true) {
std::cin >> num;
sum += num;
std::cout << sum << std::endl;
}
}
My script should looks like that:
for i in 1 2 3 4; do
echo "$i" > program
read program to line;
echo $((line * line))
done
If in program I have for(int i = 1; i <= 4; ++i), then I can do something like that:
exec 4< <(./program); # Just read from program
for i in 1 2 3 4; do
read <&4 line;
echo "sh: $((line * line))";
done
For more look here. From the other hand, if in program I have std::cout << sum * sum;, then solution could be:
exec &3> >(./program); # Write to program
for i in 1 2 3 4; do
echo "$i" > &3
done
My problem is two way communication with other process / program. I don't have to use exec. I cannot install third party software. Bash-only solution, without files, will be nice.
If I run other process, it will be nice to know pid to kill that at the end of script.
I think about communication with two or maybe three processes in the future. Output of firs program may dependents on output of second program and also in second side. Like communicator of processes.
However, I cannot recompile programs and change something. I have only stdin and stdout communication in programs.
If you have bash which is newer than 4.0, you can use coproc.
However, don't forget that the input/output of the command you want to communicate might be buffered.
In that case you should wrap the command with something like stdbuf -i0 -o0
Reference: How to make output of any shell command unbuffered?
Here's an example
#!/bin/bash
coproc mycoproc {
./a.out # your C++ code
}
# input to "std::cin >> num;"
echo "1" >&${mycoproc[1]}
# get output from "std::cout << sum << std::endl;"
# "-t 3" means that it waits for 3 seconds
read -t 3 -u ${mycoproc[0]} var
# print it
echo $var
echo "2" >&${mycoproc[1]}
read -t 3 -u ${mycoproc[0]} var
echo $var
echo "3" >&${mycoproc[1]}
read -t 3 -u ${mycoproc[0]} var
echo $var
# you can get PID
kill $mycoproc_PID
output will be
1
3
6
If your bash is older than 4.0, using mkfifo can do the same thing like:
#!/bin/bash
mkfifo f1 f2
exec 4<> f1
exec 5<> f2
./a.out < f1 > f2 &
echo "1" >&4
read -t 3 -u 5 var
echo $var
rm f1 f2
Considering that your C++ program reads from standard output, and prints to standard output, it's easy to put it inside a simple chain of pipes:
command_that_writes_output | your_cpp_program | command_that_handle_output
In your specific case you probably need to modify the program to only handle one single input and writing one single output, and remove the loop. Because then you can do it very simple, like this:
for i in 1 2 3 4; do
result=`echo $i | ./program`
echo $((result * result))
done
I have a perl script that works fine when I run it using perl filename, however when I use the command
perl -w logint > logintime.html
I get this error
Use of uninitialized value $days in multiplication (*) at logint line 5, <LAST> line 3.
It repeats this from line 3-47
This is the perl code
#!/usr/bin/perl
open LAST, "last |";
while (<LAST>) {
if (($name,$days,$hours,$mins) = /^(\w+).+\((?:(\d+)\+)?(\d+):(\d+)/) {
$TIMES{$name} += 1440 * $days + 60 * $hours + $mins;
}
}
foreach (sort keys %TIMES) {
print "$_ $TIMES{$_}\n";
}
This is how I'm attempting to output it.
#!/bin/bash
echo $HDR > ~/public_html/logintime.html
perl -w logint > logintime.html
echo $FTR >> ~/public_html/logintime.html
This is just a warning, it's not an error. You're seeing it when you run that command because '-w' is the warnings pragma.
You could also put it at the end of your shebang
#!/usr/bin/perl -w
Or 'use warnings;'. Anyway, the warning is just saying it doesn't have a value. It looks like you're reading the last log to see who last logged in, the output can be different depending on what OS you're on. I would confirm it's working as expected and getting the correct values.
It's also best practice to use 'use strict;'.
I am trying to write a Perl script to do an SNMP get. It should work like the following command:
snmpget -v 3 -l authNoPriv -a MD5 -u V3User -A V3Password 10.0.1.203 sysUpTime.0
Returns:
SNMPv2-MIB::sysUpTime.0 = Timeticks: (492505406) 57 days, 0:04:14.06
But my Perl script returns the following:
ERROR: Received usmStatsUnknownUserNames.0 Report-PDU with value 1 during synchronization.
Last but not least, here is the Perl script:
use strict;
use warnings;
use Net::SNMP;
my $desc = 'sysUpTime.0';
my ($session, $error) = Net::SNMP->session(
-hostname => '10.0.1.202',
-version => 'snmpv3',
-username => 'V3User',
-authprotocol => 'md5',
-authpassword => 'V3Password'
);
if (!defined($session)) {
printf("ERROR: %s.\n", $error);
exit 1;
}
my $response = $session->get_request($desc);
my %pdesc = %{$response};
my $err = $session->error;
if ($err){
return 1;
}
print %pdesc;
exit 0;
I called the Perl script and snmpget on the same (Linux) machine. What could be causing this and how can I fix it?
As PrgmError points out, you're using a different IP address in your Perl script than in your snmpget command; I would double check that. The particular error you're getting indicates that your username is wrong; if the IP mismatch was simply a typo in your question, I would double check the username next.
A few other points about your Perl script:
Use die
You should use die instead of printf and exit since die will print the line number where it was invoked. This will make debugging your script much easier if there are multiple places it could fail:
die "Error: $error" if not defined $session;
will print something like
Error: foo bar at foo.pl line 17.
Also, using return inside an if statement doesn't make any sense; I think you meant to use
if ($err) {
exit 1;
}
but you should die with the specific error message you get instead of silently failing:
die $err if $err;
Fix arguments to get_request
Your invocation of the get_request method looks wrong. According to the docs, you should be calling it like this:
my $response = $session->get_request(-varbindlist => [ $oid ]);
Note that Net::SNMP only works with numeric OIDs, so you'll have to change sysUpTime.0 to 1.3.6.1.2.1.1.3.0.
Looking at your script I noticed that hostname value has 10.0.1.202
but the snmpget command you're using has 10.0.1.203
wrong IP by any chance?
Is there a way to parse input and output from bash commands in an interactive terminal before they reach the screen ? I was thinking maybe something in .bashrc, but I'm new to using bash.
For example:
I type "ls /home/foo/bar/"
That gets passed through a script that replaces all instances of 'bar' with 'eggs'
"ls /home/foo/eggs/" gets executed
The output gets sent back to the replace script
The output of the script is sent to the screen
Yes. Here's something I wrote for my own use, to wrap old command line Fortran programs that ask for file-paths. It allows escaping back to the shell for e.g. running 'ls'. This only works one way, i.e. intercepts user-input and then passes it on to a program, but gets you most of what you want. You can adapt it to your needs.
#!/usr/bin/perl
# shwrap.pl - Wrap any process for convenient escape to the shell.
# ire_and_curses, September 2006
use strict;
use warnings;
# Check args
my $executable = shift || die "Usage: shwrap.pl executable";
my #escape_chars = ('#'); # Escape to shell with these chars
my $exit = 'exit'; # Exit string for quick termination
open my $exe_fh, "|$executable #ARGV" or die "Cannot pipe to program $executable: $!";
# Set magic buffer autoflush on...
select((select($exe_fh), $| = 1)[0]);
# Accept input until the child process terminates or is terminated...
while ( 1 ) {
chomp(my $input = <STDIN>);
# End if we receive the special exit string...
if ( $input =~ m/$exit/ ) {
close $exe_fh;
print "$0: Terminated child process...\n";
exit;
}
foreach my $char ( #escape_chars ) {
# Escape to the shell if the input starts with an escape character...
if ( my ($command) = $input =~ m/^$char(.*)/ ) {
system $command;
}
# Otherwise pass the input on to the executable...
else {
print $exe_fh "$input\n";
}
}
}