How to convert an integer into a string of many characters padded with 0s in bash. To do this in C: sprintf(buffer, “%08d”, n); which convert integer n to a 8-character string padded with leading 0s. How to padding a integer with 0s in bash? In bash, you can also use printf For the previous…
How to find the disk space left for a file on Linux? For example, a program may append data to a file: /mnt/logs/app-log.log How to find which partition the app-log.log is on and how much disk space left on that partition? Use this command: $ df -B1 /mnt/logs/app-log.log | tail -1 | cut -d’ ‘…
How to get the output of a system command in C? The system function is handy. But how to get the output? popen is a useful function for this purpose: https://www.systutorials.com/docs/linux/man/3p-popen/ You can use normal file operation functions like fgets to read file content from the file opened by popen.
How to hard reset an Amazon Kindle 5? First, press and hold the power button for 30 seconds. Second, release the power button and wait for the kindle to restart. After a while, the progress bar appear and kindle is rebooting.
How to convert a latex file to a single page html? htlatex is a good choice. On Fedora, install it by yum install texlive-tex4ht. To generate the HTML page from a latex file doc.tex: htlatex doc You can use the latex2html (can be installed on Fedora by yum install latex2html). $ latex2html -split +0 -info…
How to convert HTML file to a text on Linux? You can use html2text (can be installed on Fedora by yum install html2text): $ html2text ${html_file} ${html_file} is the html file to be converted. The converted text will be printed to the STDOUT. You can redirect it to a file if it is needed. Adding…
How to use ibus for inputting Chinese in Cinnamon on Fedora 19? By default, ibus is not started. If I manually start it by run $ ibus-daemon The ibus daemon is started and an icon appears in the tray area. However, no Chinese is inputted to the programs even it is turned on in the…
How to convert seconds since the epoch (1970-01-01 UTC) to a date in Linux? For example, Convert the time stamp 1349361711.169942 to Thu Oct 4 22:41:51 HKT 2012 You can use the date command on Linux to convert the time formats. For converting the time stamp 1349361711.169942 to the normal data format: $ date -d…
Cinnamon does not work well with gdm. And there is no meaning to use gdm when using Cinnamon. On Fedora, the default one id gdm. How to replace gdm with lightdm on Fedora? First, install lightdm if it is not installed yet: # yum install lightdm lightdm-gtk Then, disable gdm service and make the lightdm…
Any GUI tools to crop PDF file margins on Linux? I use krop: http://arminstraub.com/computer/krop krop is a simple graphical tool to crop the pages of PDF files. To install krop on Fedora: # yum install krop
How to tell whether the shell is run in screen? For example, I run screen and it starts a bash environment. How to tell in the bash, whether it is run by screen or it is a normal bash environment? It can be identified by checking the TERM environment variable: In a bash in screen:…
How to install the Cinnamon desktop environment on Fedora 19? On Fedora 19: # yum groupinstall ‘Cinnamon Desktop’ to install the packages needed for the Cinnamon desktop environment. Then, in the login screen, select ‘Cinnamon’ in the “Session” menu and you will start the Cinnamon desktop environment.
I have seen the question Better way to count total page views? I think, the better way is.. We can save the number of page views in the database. It is acceptable. But, it is not fulfilling my requirement, if many different users can appear to have the same IP Address (e.g, if they are…
With Gnome 3, I try to start a vncserver with $ vncserver -geometry 1024×768 to start a vnc server with geometry 1024×768, which works well with Gnome 2 before. This also works for twm. However, after I connect to the vnc server, the resolution is not 1024×768. I change the geometry to other resolution and…
I have a “t_form” table and a “t_attribute” table. It looks a little bit like below. Form table form_id | form_name | description ———————————– 1 | Laptop | Possible attributes are Model, Screen Size, OS, Cd Player 2 | Mobile | Possible attributes are Model, OS 3 | Tablet | Possible attributes are Model, Screen…
How to make a static library (.a) on Linux? How to generate a library from C programs in files lib1.c and lib2.c: $ gcc -c lib1.c lib2.c Create a library “libmy.a” using ar: $ ar -cvq libmy.a lib1.o lib2.o You can also list the files in a library with ar: $ ar -t libmy.a You…
How to install JRE for Chrome on Linux x86-64? Use JRE from Oracle on Fedora Linux x86-64 as the example: Download jre from http://java.com/en/download/manual.jsp?locale=en#lin . Select Linux x64. Install it by # yum install jre-7u40-linux-x64.rpm (the downloaded rpm). Make a softlink of the plugin:$ cd ~/.mozilla/plugins/; ln -s /usr/java/jre1.7.0_40/lib/amd64/libnpjp2.so ./ Restart Chrome and browse chrome://plugins/…
The Kindle Library Web interface only provide interface to delete items one by one. How to delete multiple items from my Kindle Library? This works on Chrome. First, browse deki.js to find the javascript for the “DeKi: Delete Kindle Items” plugin. Press “Ctrl + A” then “Ctrl + C” to copy all the javascript code….
How to set an environment variable in bash? The syntax in bash for setting an environment variable is as follows. export VARIABLE=value Note that there is no space among the variable, the equals sign (“=”) and the value. If the value has spaces, the value should be put in quotes. To check it: echo $VARIABLE…
How to set an environment variable in csh? To set an environment variable in csh: setenv VARIABLE value Most commands used to display/manipulate the environment variables for bash are also available for csh: https://www.systutorials.com/qa/476/how-to-set-an-environment-variable-in-bash