stderr

问题 I'm writing a Perl script which uses an external script. The external script must run from a specific directory so I found the following useful: use IPC::System::Simple qw(capture); my @args = ('external script path...', 'arg1', ...); my $out = capture( [0], "cd $dir ; @args" ); Sometimes the external script writes stuff to STDERR but still returns 0. I wish to capture these times and confess (or die ). Since I don't control the return value of the external script, I thought maybe I could

问题 First question, ahhhh! Does anyone know / have info about why mongoose writes its debug log to stderr? Is there anyway to write it to stdout? 回答1: The debug option accepts a function instead of a boolean: mongoose.set("debug", function (collection, method, paramA, paramB, paramC) { console.log(collection) console.log(method) console.log(paramA) console.log(paramB) console.log(paramC) }) The reason I put paramA, paramB, paramC is because the arguments are dependent upon the method and options

问题 I have the following request library(RCurl) res=getURL("http://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=RCurl&btnG=Search", .opts=list(verbose = TRUE) ) and would like to capture the verbose output of the call (i.e., what is printed in red in the R console). I thought that the output lines are messages and are therefore printed to stderr() . The following works for messages sink(textConnection("test","w"),type="message") message("test message") sink(stderr(),type="message") test #[1]

问题 A bash script is run from cron, stderr is redirected to a logfile, this all works fine. The code is: */10 5-22 * * * /opt/scripts/sql_fetch 2>> /opt/scripts/logfile.txt I want to prepend the date to every line in the log file, this does not work, the code is: */10 5-22 * * * /opt/scripts/sql_fetch 2>> ( /opt/scripts/predate.sh >> /opt/scripts/logfile.txt ) The predate.sh script looks as follows: #!/bin/bash while read line ; do echo "$(date): ${line}" done So the second bit of code doesn't

问题 There're lots of print function ( python 2.7 ) in my program. Is there any way I can add a few lines then all the output can be redirected to stderr ? What I want is python codes but not linux pipeline. For example, my program is like: print 'hello world' I would like to add some codes like: redirect_output_to_stderr() print 'hello world' Then all the output can be redirected to stderr . I know print >> sys.stderr, 'hello world' can achieve my goal, but is it any way that can prevent from

问题 Curious about how the handle STDERR works? Lets keep it down to say Batch Files to keep it simple and focused? I know that many programming languages accept STDERR, so I don't know if maybe uses are different across the board or maybe there is a common function for all programming languages? If anyone can provide some examples on common usage that you have seen or an explanation of why someone may utilize it for ??? situation that would be awesome. Thanks in advance! 回答1: Usually you would

问题 So I am trying to load test a REST API which returns a JSON value. To do that I am creating multiple instances of the perl script. The Perl script basically calls that URL, and tries to decode_json . Obviously when substantial load is generated, it fails. Now the problem I face is- An error is displayed on command prompt but does not write that error message in a file. The error message is malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "Can

问题 I'm using a grid engine to run R scripts. The STDERR is taken seriously under this setup, so I would like to keep it clean and have only real/serious/fatal errors printed to STDERR. The problem is my R script generate various STDERR messages which are not really serious warnings... for example, scan seems to print to STDERR the number of items it read. Can I redirect (from within R) STDERR to STDOUT? 回答1: Look at the help page for sink() : ‘sink’ diverts R output to a connection. If ‘file’ is

问题 I'm using a grid engine to run R scripts. The STDERR is taken seriously under this setup, so I would like to keep it clean and have only real/serious/fatal errors printed to STDERR. The problem is my R script generate various STDERR messages which are not really serious warnings... for example, scan seems to print to STDERR the number of items it read. Can I redirect (from within R) STDERR to STDOUT? 回答1: Look at the help page for sink() : ‘sink’ diverts R output to a connection. If ‘file’ is

问题 I need to close stdout and stderr for one of my C program. How is it possible without exiting the program in execution? 回答1: What have you tried? Doesn't fclose work? 回答2: You can just: fclose(stdout); fclose(stderr); For anybody wondering why you might want to do this, this is a fairly common task for a daemon/service process on Unix. However you should be aware that closing a file descriptor may have unintended consequences: When you open new files these now free descriptors will be used.