I would like to know if there is any man page documenting the construction of the most basic script commands like
for each, and all the relative switches, like
-ge, and so on.
You have to look at the manual for the specific shell you are using as the exact syntax for using these constructs can vary between shells. Most likely you are using
bash, so you would do
man bash. Although there are many cases where you might be using something else. For example many distros use a
POSIX shell for boot scripts (eg Debian uses
dash) or a least use
POSIX compliant mode. Usually you can do
man sh to get the documentation in this case (this will be linked to the man page for the shell used if it is not the original
sh or Bourne shell).
If you are unsure which shell you are using, see this question - determine shell in script during runtime
Another thing work mentioning is the
help builtin for bash, it gives an abbreviated version of what is in the manual for the various builtin commands/flow control statements etc. You can use
help on its own to see a full list of what is available, otherwise you can try things like
help test and
Have a look at the man page for the shell you're using. For
bash, the flow control statements are documented under 'SHELL GRAMMAR' -> 'Compound Commands'.
These are builtins of the shell you are using. So,
man bash or equivalent for your shell. Particularly for
bash, the man page is not too long and a very good read. Go through it and you will have a much better feeling what's possible and how stuff works (at least you know it exists for future reference).