How to get a file’s size in Python from the full path of a file? You can use this piece of Python code: os.path.getsize(file_path) It returns the size in bytes. It raises os.error if the file does not exist or is inaccessible. Manual of os.path.getsize(): https://docs.python.org/2/library/os.path.html#os.path.getsize
How to get the file extension from a filename in Python? For example, I would like to get “.txt” from “file.txt”. The Python code: >>> name, ext = os.path.splitext(‘file.txt’) >>> name ‘file’ >>> ext ‘.txt’ Manual of os.path.splitext: https://docs.python.org/2/library/os.path.html#os.path.splitext
How to detect the #hash and get the hash in JavaScript? It’s better if no additional library is needed. That said, jquery is fine if it is needed. You can use this piece of JavaScript code: if (window.location.hash) { // hash found var hash = window.location.hash.substring(1); } else { // No hash }
We have 2 static .a libraries and we would like to merge them into a single one for easier usage. How to merge 2 .a libraries to one .a library on Linux? With GNU ar, you can specify the single command-line option -M and control it with a script supplied via standard input, like the…
I use curl to send requests to remote servers like following command. curl http://example.com/send –date-urlencode “data=hello” However, it is blocked by the network proxy squid in some networks with message like (some info anonymized with “…”): ERROR The requested URL could not be retrieved POST /… HTTP/1.1 Proxy-Authorization: Basic … User-Agent: Mozilla/4.0 (compatible;) Host: ……
What’s the error code conventions on Linux and Windows? Linux and Windows use 0 to indicate that the operation is successful and an integer that is larger than 0 for some errors. Linux System Error Codes On Linux, the system error codes is defined in 2 headers which you can find on your own box:…
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…
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 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,…
How to import 3rd party libraries (e.g. not standard libraries) in OCaml? An answer by Gabriel Scherer on how to import Batteries is just great and answers this question with much information. Although it is for Batteries, the method is general. The OCaml compiler (or toplevel, etc.) will find with no additional information only the…
I backup my iPhone with iTune to my local computer. Where can I find out the backup files of my iPhone by iTune? And how to get the real files (like songs, notes, etc.) from the backup files? The location of the backup files from iTune It depends on the computer’s operating system: Mac: ~/Library/Application…
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…
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…
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.
What is the strcmp and strncmp implementation in glibc? strcmp implementation in glibc 2.16: string/strcmp.c /* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU…
Converting a string to a long in C is a common operation that can be useful in various programming tasks. In this post, we will explore how to use the strtol and strtoul C library functions to convert a string to a long in C. Using strtol and strtoul The strtol and strtoul functions are…
Seems the input method on Linux (ibus) does not work well with Chrome. But other programs, e.g. thunderbird, has not problem with ibus at all. What’s wrong with Chrome or ibus? Check whether the “Qt IBus library and Qt input method plugin” is installed. If not, installing it and restarting ibus may help: # yum…
How to efficiently archive a very large sparse file, say 1TB? The sparse file may contains a small amount of data, say 32MB. SEEK_HOLE and SEEK_DATA The SEEK_HOLE/SEEK_DATA functionalities play the trick and makes `tar` and `cp` handle the large sparse file very efficiently. `lseek` with `SEEK_HOLE` returns the offset of the start of the…
This post is about the Spring Shell technology and its use in java. Experts of java development India have shared their best knowledge in this post for Spring Shell with the community people. If you have anything to ask, do it at the end. Technology: It is command line tool for Java applications to interact…
Linux is a great platform for software development targeting servers or backends. In general, working on Linux is very productive. The problem that beginners on Linux face is the the learning curve is steep at the beginning. But believe me, after you get through the initial green steep learning step as in the figure below…