What you'll see depends on the content of the files in the dragon directory.
zcat -rf ~/dragon : find all files in the ~/dragon folder and send their content to stdout. Files compressed with gzip will be uncompressed before their content is sent to stdout. I guess most of the files are either text or text compressed with gzip. Looks to me these are kind of log files. As the zcat command uncompresses all the files, the result is expected to be text only. However, the -f flag forces zcat to process any kind of file, so if there happen to be a binary file (such as a photo or audio file for example) its content will be sent to stdout. zcat can operate on petabytes without problems.| output of the previous command (texts generated by zcat) is fed to the input of the next commandsort : the lines are sorted lexicographically (dictionary order). Note that sort must read all the input to operate, because you have to read up to the last line to correctly sort all the lines. a few Mb are OK, a few Gb could be hard for your computer, a hundred Gb or a few Tb would definitely fail. the sorted lines are sent to stdout.| stdout of previous command (ie sorted lines) are fed to the next commandgrep -iaE -A 5 'cpu[1-7].*(8[0-9]|9[0-9]|100)' : it filters lines of text. Only lines that match the search pattern are printed. What is searched exactly? Any line that contains the word cpu with a number between 1 and 7 inclusive (cpu[1-7]), then anything (.*), then either an 8 and another digit (8[0-9]), a 9 with another digit (9[0-9]) or 100. cpu can be written in upper or lower case due to the -i option. grep will search through data even if it does not look like text thanks to the -a option (remember the zcat -f option). -E enables Extended Regular Expressions which allow you to express more complex patterns, and -A 5 will print the matching line and the next 5 lines, whether they match the search pattern or not.|...tee cpu.txt print input (lines from previous commands) to both stdout (most probably your screen at this point) and to a file named cpu.txt
So what will you get? Again, hard to tell exactly but definitely lines of text that indicate which processor was above 80% usage. Maybe things like this:
2022-10-11T21:42:17.12451 warning CPU3 went mad at 98% usage for more than 1 minute. Over heating
bla bla bla 1
bla bla bla 2
bla bla bla 3
2022-10-11T21:43:02.5460 warning cpu2 at 86% usage for more than 3 days. consider upgrading your hardware
bla bla bla 1
bla bla bla 2
bla bla bla 3
bla bla bla 4
bla bla bla 5
If you don't see anything, there was no CPU above 80% in your files.
