How many arguments are passed to the command by the shell:

Question

I want to find out how many arguments are passed to the command by the shell:

echo "It's "'funny how'" it's done."

It is 1 argument, because first ' turn off the " after s , and the ' after turn off following " , so first " matches the last ".

For

"<bar bar -b "-a" '-r' >bar bar bar"

I don't understand why 5 argument are passed to the command by shell

pig pig pig

enter image description here

6   arguments passed to command by shell

Possible duplicate of [What are the special dollar sign shell variables?](https://stackoverflow.com/q/5163144/608639), [What do $? $0 $1 $2 mean in shell script?](https://stackoverflow.com/q/29258603/608639) and friends. — jww, Oct 26 '19 at 00:27
Also see [Markdown help](https://stackoverflow.com/editing-help) in the [Help Center](https://stackoverflow.com/help). — jww, Oct 26 '19 at 00:32
You say "I don't understand why 5 argument are passed to the command", then you show "6 arguments passed to command by shell". Why do you say 5 but show 6? — that other guy, Oct 26 '19 at 00:45
not the dfference between `set -- "It's "'funny how'" it's done."; echo $# ; set -- "It's " 'funny how' " it's done." ; echo $#`. ($# is the number of arguments visible to the shell, `set --` puts whatever follows as the arguments to the current shell process, so you can also do `echo $3` for instance. Good luck. — shellter, Oct 26 '19 at 02:19
**DO NOT post images of code, data, error messages, etc.** - copy or type the text into the question. https://stackoverflow.com/help/how-to-ask — Rob, Oct 26 '19 at 10:46

score 1 · Answer 1 · edited Oct 26 '19 at 10:12

Bash converts its input to tokens based on the sequence

Quoting
Expansion (brace expansion, tilde expansion, parameter and variable expansion, command substitution, arithmetic expansion, word splitting, and pathname expansion)

Applying the above to the: echo "It's "'funny how'" it's done.":

de-quoting will result in 3 replacements ('*' indicate quoted space)
1. double quoted It's*
2. Single quoted funny*how
3. Single quoted *it's*done.
The word splitting looks for unquoted spaces to separate into arguments. Given no (unquoted) spaces, all the above are combined into one argument. It's*funny*how*it's*done.

Note that quoting are not nested, as implied by the question (e.g., single quote within double quotes does NOT have special meaning).

Following on <pig pig -x " " -z -r" " >pig pig pig ('*' is quoted space, '_' is unquoted space).

de-quoting will result in 2 replacements ('*' indicate quoted space)
1. Unquoted <pig_pig_-x_ 2, Double quoted *
2. Unquoted _-z_-r
3. Double quoted *
4. Unquoted '_>pig_pig_pig`
Word splitting will process the combined <pig_pig_-x_*_-z_-r*_>pig_pig_pig. Splitting on unquoted spaces: "pig", "pig", "pig". The 'pig' will be processed by the shell: redirect input and output. Resulting in 7 parameter.

1 Answers1