I got to know Linux From Scratch soon after I bought my desktop machine. My first attampt failed at making gcc to setup the “cross-compile” environment. About four years later I picked it up and finally went through my first pass of building LFS. My destop machine has been running LFS happily since then. Two experiences are briefly note down: 1) break dependency circle with building twice; 2) reconfig kernel and build with additional modules.

The following excellent articles in the past two days taught me a lot about how the loader does relocation for ELF executables and how thread local storage is handled:

• Load-time relocation of shared libraries
• Position Independent Code (PIC) in shared libraries
• Position Independent Code (PIC) in shared libraries on x64
• A Deep dive into (implicit) Thread Local Storage
• All about thread-local storage

The Ext4 file system on our server is corrupted, causing the folder having all my latest simulator code and experimental data disappeared.

This post tells how I get the data back and fix the file system.

This post introduces how apply Linux commands to selective targets.

A server machine failed at upgrading from Ubuntu14.04 to Ubuntu16.04, and many packages are left in half-installed status, even apt is not working. I struggled several days to fix those broken packages, and this post documents some tricks I learnt.

This post introduces how Linux command find is used to find file or directory with certain attributes.

This post introduces how to use escape code to get colorful output in a terminal.

This post contains three shortcuts of bash.

Tip 102:
The terminal text can be cleared by typing Ctrl+L. It is the same as the command clear.

This post contains a tip from TACC helping debug the shell script.

Under some circumstances, I would like to launch the process, then let other programs attach to it. No matter how fast can I type, it is impossible for me to bind the processes from the very beginning. The solution is let the script to launch the process but suspend it immediately.

#!/bin/bash
$@ &
PID=$!
kill -STOP $PID
echo $PID
wait $PID

The script earns enough time for you to do your operations in another terminal, then to resume the process:

kill -CONT $PID

Note: need to replace $PID with the number printed in the first terminal.

With huge files, tasks that as simple as removing first or last several lines could become hard. If you try to open a huge file with vim, the chance is that the system gets stuck struggling to load the huge file into memory. This post has several alternative approaches to delete lines from huge files.

To invoke an editor for a long command, try ctrl-x e (that is holding control key press x then e).

This post contains four tips from TACC making the shell command cd more versatile.

Two useful tips from TACC tips regarding compiler macro expanding.

Tip 120:
Want to know what MACROS are predefined by the GCC and Intel compilers? Do

gcc -dM -E - < /dev/null > gcc_defined_macros.txt
icc -dM -E - < /dev/null > icc_defined_macros.txt

The flag -E in the tip is telling the compiler to expand macros.

Tip 69:
Having trouble figuring out how a macro is being expanded? Try pasting the line into a terminal and adding a -E. For example try changing mpicc -DFOO -DBAR -c foo.c into mpicc -DFOO -DBAR -E foo.c > foo.i and look at the foo.i file.

The bash-completion package does not handle command make, while we can extend the completion support for make by adding bash configurations with keyword complete.

The command line prompt in Linux could be customized to user’s need. It is achieved by modifying a series of environment variables, such as PS1, PROMPT_COMMAND and PS2.

Device node is a file-like abstraction in Linux for user to interact with devices. It could map the operations (read, write, fasync etc.) performed on the file to the associated device. Otherwise, user application needs to be executed with privilege to do memory map before using the device, and programer needs to know the physical address.

After reinstall OS, the SD card reader on my laptop stops work again. Because this time I use Linux Mint, which is based on higher version kernel, I encountered more troubles to drive the SD card reader.

Three steps, five errors and solutions are recorded.

After reinstall OS, the SD card reader on my laptop stops work again. Because this time I use Linux Mint, which is based on higher version kernel, I encountered more troubles to drive the SD card reader.

Three steps, five errors and solutions are recorded.

Two tips, one to find processor information, another for detailed system configurations.
Updated with two more tips on January 23, 2018. One to find memory information, another for interrupt information.
Updated with one more tip from TACC on July 23, 2018. It gives HTML view.