I have a process MYPID=18686 that I am monitoring with top. When the process dies, the output file is empty. My end goal is just to record cpu usage over the lifetime of that process. Specifying -n 1000 -d 5 is a cheap workaround that runs top for the expected lifetime of the process. The tail -1 was to elimi…
Tag: linux
Linux split a file in two columns
I have the following file that contains 2 columns : How is possible to split the file in 2 other files, each column in a file like this: File1 File2 Answer Perl 1-liner using (abusing) the fact that print goes to STDOUT, i.e. file descriptor 1, and warn goes to STDERR, i.e. file descriptor 2: You could, of co…
Are BIGNUM BN_ functions deprecated in openssl 1.1?
I was compiling some ‘C’ code that uses openssl under Fedora 27 (version 1.1.0g-1). I made some needed changes (from the 1.0.2 version of my code) and things now compile o.k. again. I then tried to compile with the option “OPENSSL_API_COMPAT=0x10100000L” which I understand causes the c…
Pcap4j Library: Exception in thread “main” java.io.IOException: No NIF to capture
When I capture packets, I get the following error: Exception in thread “main” java.io.IOException: No NIF to capture. The code is: But I run this code with sudo command, it is running. Why don’t I run this code without sudo? I should run this code without sudo. How can I run this code? Answe…
Does all linux users are present on /etc/passwd? [closed]
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack …
Nginx returns 404 not found when access file on server
I have a server(Ubuntu 16.04) and a user called coxier. I configure Nginx to Proxy Requests. I create a file etc/nginx/sites-available/myproject. In this flask project, server receive request and then generate a .gif file for this request. At first I directly I use flask#send_file to send gif file about 1MB, …
Run bash command from python and capture file object
in jupyter notebook I can run the following command and get a list of file objects that I can then open: I have tried the following: But I can only get a string object not file objects that I can then open and get data from. Answer Filenames are strings. That’s what you pass to open to get a file
How to grep for a matching word, not the surrounding line, with a wildcard?
Maybe an odd question, but I’m attempting to grep the output of a command to select just the matching word and not the line. This word also has a wildcard in it. The first and second sections of the command check the git log for a file and grabs the line pertaining to the date and time of creation. I…
How can “plugins” loaded by libdl refer to symbols in the program which loaded them?
Imagine that you have an application with a plugin based architecture, where each plugin is a *.so file that is dynamically loaded with dlopen(). The main application can refer to symbols via dlsym(), and so it may call functions of the plugin. How can the plugin call functions of the main application? I know…
How to log to /var/log/mail.log using rsyslogd?
I am currently playing around with logging under Linux. I have made the following very simple test application (in plain C): This “application” compiles, and when I execute it, it generates an entry in /var/log/syslog, but no entry in /var/log/mail.log and no entry in /var/log/mail.err. Could some…