How to use printf "%q " in bash? -

i print out augments of function file. told command printf "%q ", instruction following,

# man printf %q     argument printed in format can reused shell input, escaping non-print‐           able characters proposed posix $'' syntax. 

on basis of instruction above, tried following code.

#!/bin/bash # file name : print_out_function_augs.sh  output_file='output.txt'  function print_augs() {   printf "%q " "$@" >> "${output_file}"   echo >> "${output_file}" }  print_augs 'b c'  cat "${output_file}" rm "${output_file}" 

and run

bash print_out_function_augs.sh 

the results following,

a b\ c 

i expected results as

a 'b c' 

which original augments print_augs function.

why output , original augments different? or can print out original augments are?

thank much.

bear in mind when using %q:

argument printed in format can reused shell input, escaping non-printable characters proposed posix $'' syntax.

emphasis mine. printf free reformat arguments way likes as long input can reused in shell. not reason input looks way does.

in bash ' character string delimiter, how tell bash "the following string contains special characters spaces, , these special characters should not parsed bash". quotes not passed commands called. command sees this:

command:   printf "%q" 'b c'  received args:   printf::arg0:  printf   printf::arg1:  %q   printf::arg2:    printf::arg3:  b c 

note arg3 not have quotes surrounding it. bash not pass them on.

when printf prints args out, it not know there quotes around b c, not print them. know space between 'b' , 'c' special shell character, , puts \ in front escape it.

this true bash functions/commands, bear in mind same happens when call print_augs too.

if want maintain quotes around strings, you'll need double quote them bash doesn't parse them:

function print_augs2() {   echo "$@" >> "${output_file}" }  print_augs2 "'b c'"  # output: 'b c'