1. The order of precedence of operators in POSIX extended regular expression is as follows.

   1. Collation-related bracket symbols [==], [::], [..]
   2. Escaped characters \
   3. Character set (bracket expression) []
   4. Grouping ()
   5. Single-character-ERE duplication *, +, ?, {m,n}
   6. Concatenation
   7. Anchoring ^, $
   8. Alternation |

2. Some regular expression patterns are defined using a single leading backslash, e.g., \s, \b, etc. However, since special …

The simplest way to check whether a Linux system is running systemd, upstart or SysV is by running the following command.

ps -p1 | grep "init\|upstart\|systemd"

References

How to determine which system manager is running on Linux System

How to know if I am using systemd on Linux?

I countered the issue when using PySpark locally (the issue can happen to a cluster as well). It turned out to be caused by a misconfiguration of the environment variable JAVA_HOME in Docker.

References

PySpark: Exception: Java gateway process exited before sending the driver its port number

FAT32

FAT32 is an outdated filesystem. The maximum size for a single file is 4G. You should instead exFAT instead of FAT32 where possible.

exFAT

exFAT is great cross-platform filesystem that is support out-of-box by Windows, Linux and macOS. There is practically no limit (big enough for average users) on …

1. ttf-arphic-uming, ttf-wqy-microhei, ttf-wqy-zenhei, xfonts-wqy and ttf-opensymbol are some packages related to Chinese fonts.

2. If you have Adobe Reader installed on your computer, you can use Adobe Chinese fonts for free.

3. To check Chinese fonts installed on your computer, you can use the command fc-list :lang=zh-cn | sort.

4. To install extra …

The article 14 Practical examples of the grep command has some good examples on how to use the grep command.

1. The Perl style (option -P) regular expression is more powerful than the basic (default) and extended (option -E) regular expression. It is suggested that you use the perl style as …