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How does Bash perform an expansion on a file?
As far as rm knows, it simply receives a -v argument followed by the exact and full name of every single file in the directory. Expansion is always performed by bash itself, and always before actually running the command! Bash can perform all sorts of pathname expansions for us.
How to expand a special variable in Bash?
Basically the current bash instance we’re running takes our place as the user of another bash instance and types in the command “echo ~…” for us.
Why are there extra arguments in Bash command?
The second mistake is that extra arguments are assigned as positional parameters to the shell process that’s launched, not passed as arguments to the command. So, what you’re trying to do could be done as one of:
What do you call a pathname expansion in Bash?
Replacing patterns with pathnames is therefore known as pathname expansion. In our example above, bash notices that you have put a pathname pattern on the command line in the place where it would expect to see arguments.
What does it mean to expand a parameter in Bash?
Bash uses the value formed by expanding the rest of parameter as the new parameter; this is then expanded and that value is used in the rest of the expansion, rather than the expansion of the original parameter. This is known as indirect expansion.
How to perform pathname expansions in Bash shell?
Bash can perform all sorts of pathname expansions for us. To perform a pathname expansion, we simply write a syntactical glob pattern in the place where we want to expand pathnames. A glob is the name of the type of pattern supported by the bash shell.
Is the exclamation point subject to expansion in Bash?
The exceptions to this are the expansions of $ {! prefix *} and $ {! name [@]} described below. The exclamation point must immediately follow the left brace in order to introduce indirection. In each of the cases below, word is subject to tilde expansion, parameter expansion, command substitution, and arithmetic expansion.