How to get a 10-byte length random string in bash. Use this script to get a 10-byte string of letters: tr -dc “[:alpha:]” < /dev/urandom | head -c 10 You can also get a string of letters or numbers: tr -dc “[:alnum:]” < /dev/urandom | head -c 10 Or printable characters except space: tr -dc…
A common error for configuring cron is to use environmental variables for an account in the cron command. However, cron will run the commands without these variables defined. In the crontab -e, adding . $HOME/.profile before the commands play the trick. For example: 0 */8 * * * . $HOME/.profile; ~/bin/my-command Cron is started by…
How to automatically fill a batch of data (well structured) to the PDF form? There are lots data items, so automatically do this by a program/script is required. If you know a little bit of Python, you can achieve this in Python with some libraries. Check How can I auto-populate a PDF form in Django/Python….
Excerpt in homepage, category, tag and author pages for WordPress theme Twenty Thriteen. Also add the “read more” link after the excerpt. The patch: diff –git a/wp-content/themes/twentythirteen/content.php b/wp-content/themes/twentythirteen/content.php index 4f61b22..53b4686 100644 — a/wp-content/themes/twentythirteen/content.php +++ b/wp-content/themes/twentythirteen/content.php @@ -30,7 +30,7 @@ </div><!– .entry-meta –> </header><!– .entry-header –> – <?php if ( is_search() ) : // Only display…
I see this message in the error log of httpd: PHP Fatal error: Maximum execution time of 30 seconds exceeded in and PHP Fatal error: Allowed memory size of 268435456 bytes exhausted How to change them to a longer and larger value? To change the allowed maximum memory usage of PHP: Set memory_limit = 256M…
What are good PDF annotation tools on Linux? Preferring saving the annotation in the PDF instead of separate files or images. I find the best solution may be wine + Foxit Reader. Foxit Reader can annotate PDF files and save them. It works very well on wine. Steps to install them: Install wine # yum…
How to trap Ctrl-C in a Bash script? The piece of code: # trap ctrl-c and call ctrl_c() trap ctrl_c INT function ctrl_c() { echo echo “Ctrl-C by user” # do the jobs exit }
For example, I want to spawn many ssh background processes in one bash script: for i in `cat ./all-hosts` do ssh $i “ifconfig | grep Link” done Simply adding a & to the ssh commands does not work. Here is the script that works: for i in `cat ./all-hosts` do ssh $i “ifconfig | grep…
This tutorial introduces how to install Scala 2.9.2 on 64-bit Fedora Linux 17. There are some changes needed to make scala work on Fedora Linux 17. Please check it out in the answer. Install Java Scala depends on Java, so please install Java first. In this tutorial, we installed JDK to: /usr/java/jdk1.6.0_24/lib/. Install Scala from…
How to install Scala from the official Scala distribution? This is needed on a Linux release with older version of Scala in the repository, e.g. Fedora 12. Use the install-scala.sh script: # wget https://raw2.github.com/zma/usefulscripts/master/script/install-scala.sh # sh ./install-scala.sh VER where VER is the scala version that you want to install. First step, install and configure the…
I know the routing tables on Linux is in memory after being set. However, where are the routing table entries stored on disk? I mean where are the routing table is persistently stored so that the routing table can be reloaded like the iptables (under /etc/sysconfig/iptables on Fedora/RHEL/CentOS Linuxes). If the system uses the /etc/rc.d/init.d/network…
How to use OCaml as a script language like bash and python? It will be good that I can write a script in OCaml and directly invoke it. For example, I write a script named “script.ml” and then I can invoke it directly by $ ./script.ml Thanks! Three helloworld scripts: script3.ml #! /usr/bin/env ocaml print_string…
I frequently hear that cin is significantly slower than scanf in C++. Is this true? And how to improve the efficiency of cin? It is really nice to use most of time. One discussion about that cin is very slow is here: http://apps.topcoder.com/forums/?module=Thread&threadID=508058&start=0&mc=7 In short: cin is not always slower (can be faster actually, see…
How to import a source file to OCaml’s toplevel? Say, I want to use a function implemented in a source file in the toplevel. #use “file-name”;; Read, compile and execute source phrases from the given file. This is textual inclusion: phrases are processed just as if they were typed on standard input. The reading of…
I am writing a OCaml program but want to call some C functions provided in some source code or library. How to achieve this? Is there any good tutorials on this? A very good tutorial that is easy to follow and understand: How to wrap C functions to OCaml. A comprehensive reference manual: Chapter 19…
Which are the consistency models used for distributed systems? Papers that survey the consistency models Robert C. Steinke and Gary J. Nutt. 2004. A unified theory of shared memory consistency. J. ACM 51, 5 (September 2004), 800-849. DOI=10.1145/1017460.1017464 http://doi.acm.org/10.1145/1017460.1017464 David Mosberger. 1993. Memory consistency models. SIGOPS Oper. Syst. Rev. 27, 1 (January 1993), 18-26. DOI=10.1145/160551.160553…
How to restore a Gnome 3 session? Which means: opening all the programs running last time when I log out in Gnome 3. If your purpose is to automatically start programs after logging in Gnome, another possible method is using the autostart script: https://www.systutorials.com/qa/119/how-to-write-a-autostart-script-for-gnome Run gnome-session-properties. In the “Options” tab, select “Automatically remember running applications…
It is painful for a Linux user to use the OCaml toplevel without the readline features. Is there a method to enable/add these kinds of features in readline to the OCaml toplevel? I find 2 options that work very well for me: utop provides a beautiful interface and supports completion, colors, parenthesis matching, etc. It…
How to statically compile C and C++ projects? The compiled executable should lead no dynamical library during execution. I use gcc/g++ to compile the projects. Check this post: Statically Linking C and C++ Programs on Linux with gcc.
Hi , Thank you for your recommendation for removing the canonical link for the forum page only. However, I am am not able to find the following code in the wpf.class.php and was hoping you let us know where we can find this class so that we can modify it accordingly. (Does -1260 refer to…