from Python3, I'm trying to run a script (that I can't edit) that is looking in stdin for file names, runs some code on them and after all that, is expecting for "y/n" answer.
The whole code takes about 3 seconds at most.
How can I add "y" to the stdin after running the script?
This is the original script (written in perl):
if (! -t STDIN) {
while(my $file=<STDIN>) {
chomp $file;
printI "Getting file from STDIN : $file\n";
push(#table_files,$file);
}
close(STDIN);
}
...
<code that runs>
...
"Does it look right? (y/n) : ";
open(STDIN,"/dev/tty"); # reopen stdin cause script also takes files from stdin
my $answer=<STDIN>;
chomp($answer);
if (lc ($answer) ne "y") {die "Exiting!\n"}
Those were my tries (using the terminal):
( sleep 5 ; echo y ; ) | script.pl file1; # Takes "y" as a file instead of answer
yes | script.pl file1; # Fails because it tries to read 'y' all the time as files
This is my try in python3:
p = Popen("script.pl file1", stdout=PIPE, stderr=PIPE, stdin=PIPE, universal_newlines=True, shell=True)
(stdoutdata, stderrdata) = p.communicate(input=f'y\n') # Fails because of no delay
Any suggestions?
If there is a solution for both terminal(tcsh I believe) and python, that would be great. Thanks!!
Related
I got a script that asks 1000 times for input of 1-5, it looks like this:
insert1:
insert2:
insert3:
insert4:
insert5:
//and again 1-5
insert 1:
...in total it will get 1000 inputs
I want to write a one line script that will run the script I just described, it will insert the input that needed each time.
this is what I tried:
#!/bin/bash
./my_script.exe -l | for i in {1..200}; do for j in {1..5}; do j; done; done
You are nearly there, but do it the other way around:
for ((i=1;i<=200:i++)) ; do
for ((j=1;j<=5;j++)) ; do
echo $j
done
done | ./myscript.exe -l
You can put a # before the | to comment it out and see what the script sends to your program.
You need to differentiate between parameters which are specified after the program name like this:
program param1 param2 param3
and inputs, which a program gets by reading its stdin and are supplied like this:
printf "input1\ninput2\ninput3\n" | program
Alternative version of second command:
{ echo input1; echo input2; echo input3; } | program
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 $e;
' -- prog args | ...
Or you could fool the program into thinking it's connected to a terminal using unbuffer.
unbuffer prog args | ...
I'm seeking for ways to write data to the existing process's STDIN from external processes, and found similar question How do you stream data into the STDIN of a program from different local/remote processes in Python? in stackoverlow.
In that thread, #Michael says that we can get file descriptors of existing process in path like below, and permitted to write data into them on Linux.
/proc/$PID/fd/
So, I've created a simple script listed below to test writing data to the script's STDIN (and TTY) from external process.
#!/usr/bin/env python
import os, sys
def get_ttyname():
for f in sys.stdin, sys.stdout, sys.stderr:
if f.isatty():
return os.ttyname(f.fileno())
return None
if __name__ == "__main__":
print("Try commands below")
print("$ echo 'foobar' > {0}".format(get_ttyname()))
print("$ echo 'foobar' > /proc/{0}/fd/0".format(os.getpid()))
print("read :: [" + sys.stdin.readline() + "]")
This test script shows paths of STDIN and TTY and then, wait for one to write it's STDIN.
I launched this script and got messages below.
Try commands below
$ echo 'foobar' > /dev/pts/6
$ echo 'foobar' > /proc/3308/fd/0
So, I executed the command echo 'foobar' > /dev/pts/6 and echo 'foobar' > /proc/3308/fd/0 from other terminal. After execution of both commands, message foobar is displayed twice on the terminal the test script is running on, but that's all. The line print("read :: [" + sys.stdin.readline() + "]") was not executed.
Are there any ways to write data from external processes to the existing process's STDIN (or other file descriptors), i.e. invoke execution of the lineprint("read :: [" + sys.stdin.readline() + "]") from other processes?
Your code will not work.
/proc/pid/fd/0 is a link to the /dev/pts/6 file.
$ echo 'foobar' > /dev/pts/6
$ echo 'foobar' > /proc/pid/fd/0
Since both the commands write to the terminal. This input goes to terminal and not to the process.
It will work if stdin intially is a pipe.
For example, test.py is :
#!/usr/bin/python
import os, sys
if __name__ == "__main__":
print("Try commands below")
print("$ echo 'foobar' > /proc/{0}/fd/0".format(os.getpid()))
while True:
print("read :: [" + sys.stdin.readline() + "]")
pass
Run this as:
$ (while [ 1 ]; do sleep 1; done) | python test.py
Now from another terminal write something to /proc/pid/fd/0 and it will come to test.py
I want to leave here an example I found useful. It's a slight modification of the while true trick above that failed intermittently on my machine.
# pipe cat to your long running process
( cat ) | ./your_server &
server_pid=$!
# send an echo to your cat process that will close cat and in my hypothetical case the server too
echo "quit\n" > "/proc/$server_pid/fd/0"
It was helpful to me because for particular reasons I couldn't use mkfifo, which is perfect for this scenario.
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.
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";
}
}
}