Meeting Minutes - sh - Posix Shell Session - Day 4 - July 09, 2020
Here are the topics we covered on day four,
- importance of exitcode (or returncode)
- howto retrive last executed command’s exitcode through
${?}special variable - howto use this exitcode in if-elif-else-fi command
- howto use case-esac command
- introducing ‘for-do-done’ loop
- how this is different from regular for loop in ‘C’ programming
- iterating through static values using for loop
- introducing command substitution through
$() - how command substitution can generate dynamic values for each iteration in for loop
- importance of command substitution
- introducing ‘while-do-done’ loop
- introducing variable expansion, what exactly means ‘$’ before a word
- difference between ${var} and “${var}”
- different way to expand variables using
:+,:=,:?and:- - howto do arithmetic expansion using
$(()) - built-in special variables which ‘sh’ provides by default
- meaning of ‘${$}’
- meaning of ‘${?}’
- meaning of ‘${!}’
- running background jobs using ‘&’ seperator
- introducing ‘jobs’ command, also ‘bg’ and ‘fg’ commands