How to set and get an environment variable in C on Linux? You can use the setenv and getenv POSIX APIs to set and get environment variables. To add or change environment variable: #include <stdlib.h> int setenv(const char *envname, const char *envval, int overwrite); To get value of an environment variable: #include <stdlib.h> char *getenv(const…
For example, try to less the error messages generated by the compiler with make | less Use this command: make 2>&1 | less or, if you want stderr only: make 2>&1 >/dev/null | less
How to format outputs with cout in C++? You need IO Manipulators <iomanip>: Header providing parametric manipulators. There are also good tutorials on the Web: Output Formatting: http://arachnoid.com/cpptutor/student3.html Formatting Cout Output in C++ using iomanip: http://www.cprogramming.com/tutorial/iomanip.html
How to show the list view in iOS 7’s calendar? Is it deleted? The list view is still available in iOS 7’s calendar. To find it, just click the magnifying glass on the top right and you will see the list view.
Tutorial: How to trace a function in OCaml. Use #trace. For example, to trace function f: # let rec f n = if n = 0 then 1 else f (n – 1) * n;; val f : int -> int = <fun> # #trace f;; f is now traced. # f 4;; f <–…
How to list the functions in a .a library on Linux? You can use the nm command: The nm utility shall display symbolic information appearing in the object file, executable file, or object-file library named by file. If no symbolic information is available for a valid input file, the nm utility shall report that fact,…
g++ (version g++ (GCC) 4.8.1 20130603 (Red Hat 4.8.1-1)) report: $ g++ -std=c++11 solution.cpp -o sol solution.cpp: In function ‘int main()’: solution.cpp:50:57: sorry, unimplemented: non-trivial designated initializers not supported Stat init_stat {.depth = 0, .moves = tv, .vec = init}; ^ solution.cpp:50:57: sorry, unimplemented: non-trivial designated initializers not supported solution.cpp:50:57: sorry, unimplemented: non-trivial designated initializers…
How to mount Ext4 partitions from Linux in Windows in read-only mode? Read-only is required to ensure safety. Mounting is required so that traditional programs can use the partition without any changes. Ext2Fsd is a great tool for this. Ext2Fsd is a file system driver which allows accessing (both reading and writing) ext2, ext3 or…
How to remove cookies for a specific site/domain in Chrome? I just want to delete the cookies by one site, not the whole cookies stored by my browser. In Chrome’s settings (open chrome://settings/ in the URL bar): Search for “cookie” and you will find “Privacy” -> “Content Settings”. Click the button “Content Settings”. In the…
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 reset the Disqus WordPress plugin installation? After deactivating/activating the Disqus WordPress plugin, the ID and others are the same as the old ones. What I need is to change the Disqus forum ID for a WordPress installation. Find all the tuples in the _option table of WordPress that contains “disqus” and delete them….
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….
Which shared hosting services have SSH enabled? SSH is a great tool for management and development. Lots shared hosting services support SSH. Here is a non-complete list: Dreamhost SSH on dreamhost: http://wiki.dreamhost.com/Enabling_Shell_Access BlueHost SSH on BlueHost: http://my.bluehost.com/cgi/help/180 GoDaddy SSH on GoDaddy: http://support.godaddy.com/help/article/4942 HostGator SSH on HostGator: http://support.hostgator.com/articles/hosting-guide/lets-get-started/how-do-i-get-and-use-ssh-access HostMonster SSH on HostMonster: http://my.hostmonster.com/cgi/help/180 ServerGrove SSH on…
How to install WordPress in a sub directory while working for the whole site? Putting the WordPress files in the root directory seems messy. A method is introduced here: http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory The process to move WordPress into its own directory is as follows: Create the new location for the core WordPress files to be stored (we…
Tools to check broken links for websites. This tool is great for broken link checking: http://www.brokenlinkcheck.com/ . It check all your site automatically. W3C also has a tool to check a single page: http://validator.w3.org/checklink There is also an open-source tool LinkChecker: http://wummel.github.io/linkchecker/ If you are using WordPress, a plugin is also available: http://wordpress.org/plugins/broken-link-checker/
PuTTY is a great SSH client on Windows. However, how to save it’s profiles/sessions that I saved so that I can migrate my settings from one machine to another? PuTTY saves its settings in the registry of Windows. You can find it in the registry editor by run regedit under: HKEY_CURRENT_USERSoftwareSimonTatham You can save your…
How to set up MySQL replication. And for debugging purpose, it will be great if I can run multiple MySQL instances on a single host. To set up MySQL replication, check these tutorials: MySQL Replication MySQL replication setup You can Setup multiple MySQL instances on single server.
How to host a domain name registered in another account in one Dreamhost account. Simply trying to add the new domain, it reports: Error! You can’t add that domain: already in our system You need to delete the domain from your hosting (DNS) from the account first. Don’t worry, the domain name is still there…
How to change an attachment’s parent post in WordPress? The in WordPress posts depends on the child-parent relationship. It will be good to change the parent posts for attachments. The Change Media Parent WordPress plugin works great for me. After installing and activating it, a link to change the parent appears in the media control…