Making your script responsive
Conclusions
The basic version of the quota control script (Listing 5) aims to prevent a partition from "filling up" by combining several types of flow control in ways that try to balance efficiency with equal treatment for all users, according to the actual disk usage in any given moment. As is, however, the script deliberately misses a couple of pieces, partly due to space constraints but also to leave these enhancements as an exercise for the reader. First, the "WATCHING" section is not completely fair: Since the for loop in line 36 starts from the first index every time, over time it will delete slightly more of the first user's files than the others. To fix this, change it to make it start every time from the index following the last one used in the previous execution of the whole "WATCHING" status. (Hint: Use the $LASTINDEX variable in line 41.)
The other thing missing to make the script more efficient is code that makes it move directly from, for example, "CRITICAL" to "WATCHING" and from "WATCHING" to "EMERGENCY". Happy hacking!
PS: To safely test Listing 5, you need a folder full of non-empty files of random size. To generate this automatically, use the tricks described in [4] and [5]:
Infos
- "Tutorial – Shell Scripting" by Marco Fioretti, Linux Magazine, issue 219, February 2019, p. 84-88.
- "Tutorial – Bash Arrays" by Marco Fioretti, Linux Magazine, issue 220, March 2019, p. 84-89.
- Bash test operators: https://www.tldp.org/LDP/abs/html/tests.html
- "Generate random number between 1 and 10 with Bash Shell Script": https://stackoverflow.com/questions/8988824/generating-random-number-between-1-and-10-in-bash-shell-script
- "Create many files with random content": https://unix.stackexchange.com/questions/199863/create-many-files-with-random-content
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