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When do you Glob a variable in Bash?
Globbing takes place upon unquoted variable expansion in list contexts, that (leaving a variable unquoted) is what we sometimes call the split+glob operator. There’s no globbing in assignments to scalar variables. foo=* and foo=’*’ is the same.
How to stop the shell from globbing around a variable?
“$@” is a number of double quoted words. This could be used to execute a command with arguments. The way to stop the shell from globbing is to quote the variable expansion. (It also stops word splitting, which is usually also what you want).
How to prevent parameter expansion around a variable I want to be resolved?
Where the runprintcommand function/script being: An unquoted variable would undergo variable expansion, word-splitting (on spaces, tabs and newlines by default), and each generated word would in turn undergo filename generation (globbing).
Can a glob be saved as an array?
You can save it as an array instead of a string to use later in many cases and let the globbing happen when you define it. In your case, for example: @ilkkachu answer solved the main globbing issue. Full credit to him.
Is there a way to set nullglob in Bash?
Note that the shell option nullglob needs to be set. It is not set by default. It prevents an error in case the glob (or one of multiple globs) does not match any name. compgen is a Bash built-in that you can pass an escaped (!) pattern to, and it outputs matches, returning true or false based on whether there were any.
Is there a glob pattern matching feature in Bash?
The bash man page refers to glob patterns simply as “Pattern Matching”. First, let’s do a quick review of bash’s glob patterns. In addition to the simple wildcard characters that are fairly well known, bash also has extended globbing, which adds additional features. These extended features are enabled via the extglob option.
How to substitute a string for a parameter in Bash?
From the bash documentation: $ {parameter/pattern/string} Pattern substitution. The pattern is expanded to produce a pattern just as in pathname expansion. Parameter is expanded and the longest match of pattern against its value is replaced with string.
How are variables and command substitution used in Bash?
Bash variables and command substitution Using variables to refer to data, including the results of a command. An essential feature of programming is the ability to use a name or a label to refer to some other quantity: such as a value, or a command. This is commonly referred to as variables.
How to stop globbing in a subshell in Bash?
As an alternative to switching between set -f and set +f you could perhaps just apply a single set -f to a subshell since the environment of the parent shell would not by affected by this at all: You can turn off globbing with set -f, then turn it back on later in the script with set +f. Use while read instead.
For instance, a local variable declared in a function hides a global variable of the same name: references and assignments refer to the local variable, leaving the global variable unmodified. When the function returns, the global variable is once again visible. The shell uses dynamic scoping to control a variable’s visibility within functions.
When to use variables as global-Unix…?
Any variable not specifically exported or declared as local will be a global variable. Variables local to the function may be declared with the local builtin. These variables are visible only to the function and the commands it invokes. This is particularly important when a shell function calls other functions.
How to see global variables in a script?
You can see them by executing the env command. A global variable will be visible to everything within a single program (script) including child processes created by subshells/functions, but not across programs (scripts). Any variable not specifically exported or declared as local will be a global variable.