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  Differences between bashrc and profile in Linux

After login to a Linux system, the command console will show up with a prompt label such as # or ~, a shell command can be typed after this prompt and the system can execute the command thereafter. All these operations are handled by shell. Shell is a command language interpreter that executes commands read from the standard input device (keyboard) or from a file. There are different types of shells such as bash, ksh, csh etc. The most commonly used of them is bash and it's also the de...

1,916 0 0          LINUX PROFILE BASH BASHRC .BASHRC .PROFILE


  Unix directory hierarchy history

As a beginner user of Unix or Linux, people would frequently get confused about the use of different directories of the system.  For example, there is a /bin directory under root(/), it is used to store binary files. However, there are /usr/bin and /usr/local/bin under /usr which are used for storing binary files as well. Some systems even have /opt/bin. What are the differences among them? Though there are articles explaining different directories in *nix such as Filesystem Hierarchy Stan...

2,920 0 0          LINUX HISTORY UNIX FILESSYTEM DIRECTORY HIERARCHY


  Linus Torvalds apologizes for Linux 4.8 kernel bug

On Oct 2, Linus Torvalds proudly announced the release of Linux 4.8. But just days after the release, a bug was found in the kernel and Linus came out and apologized for this bug. I'm really sorry I applied that last series from Andrew just before doing the 4.8 release, because they cause problems, and now it is in 4.8 (and that buggy crap is marked for stable too). In particular, I just got this kernel BUG at ./include/linux/swap.h:276 and the end result was a dea...

1,238 0 0          LINUX LINUX KERNEL NEWS LINUS TORVALDS BUG_ON


  Using public key authentication in SSH

SSH is a popular cryptographic network protocol for secure network service operation. It is frequently used in remote server login. For a system administrator or software developer, SSH is frequently used to access remote servers or development servers or testing servers etc.  To login with SSH, there are different authentication mechanisms : password, public key and interactive etc. If a remote server needs to be accessed frequently, password authentication may be too troublesome as p...

1,056 0 0          LINUX DEBUG SSH PUBLIC KEY


  Format JSON data on Ubuntu

JSON now becomes a very popular data format because of its simplicity and light-weight. Nowadays many RESTful APIs will offer a choice of exchanging JSON data between the server and client. Sometimes the data may not be formatted and it cannot be easily read by human beings. It's frequently desired that the unformatted JSON data should be formatted before read. Today we will show a few ways to format JSON data on Ubuntu. Assume we have a json file test.json with below content. { "title": "Test"...

1,625 0 0          UBUNTU LINUX RUBY PYTHON NODEJS PERL JSON JQ YAJL


  Mount DD image on Linux

Yesterday, my Raspberry Pi running Arch Linux was not able to boot with error: Kernel Panic, not syncing: no init found. I spent a night on it, but could not find a working solution. The last option is easy: reinstall the system. That is really the last resort, for I do not want to re-setup everything I have done: samba server, Time Machine server, Xunlei Offline Downloader… Unable to mount the SD card The system does not boot, so I need to find a way to get into the file system to identi...

2,375 0 0          LINUX DD IMAGE


  Shortest command on Linux

Usually when we log in to a Linux system,. we may type some frequently used Linux commands such as pwd,ls, ps etc. All these commands are really simple but powerful with different options. But do you know what is the shortest command on Linux? The answer is w. According to Linux manual, w will show who is logged on and what they are doing on the system. w displays information about the users currently on the machine, and their processes. The header shows, in this order, the current time, how l...

2,902 0 0          W LINUX SHORTEST COMMAND


  A possible way to recover deleted files on Linux

Last week I was generating a MD5 sum for an virtual machine image on one OpenNebula server: # ls -l test.img -rw-r--r-- 1 root root 10486808576 Oct 12 02:21 test.img # md5sum test.img At the same time I was clearing the files on the server on another terminal and deleted the above image file mistakenly with : # rm test.img Since this image file is 10GB, it took some time to remove this file from the server, so I used the Ctrl+Z command to suspend the remove command. [1]+ Stopped ...

45,371 0 1          LINUX FILE RECOVERY