xargs

xargs & quotes

xargs treats quotes differently than the shell (bash, for example).

$ printf '"foo"bar"' | xargs printf %s\\n
xargs: unmatched double quote; by default quotes are special
to xargs unless you use the -0 option

Excerpt from man 1 xargs

-0
--null

  Input items are terminated by a null character instead of by
  whitespace, and the quotes and backslash are not special (every
  character is taken literally). Disables the end-of-file string,
  which is treated like any other argument. Useful when input items
  might contain white space, quote marks, or backslashes. The GNU
  find (and from POSIX Issue 8, IEEE Std 1003.1, 2024) -print0
  option produces input suitable for this mode.

Therefore:

$ printf '"foo"bar"' | xargs --null printf %s\\n
"foo"bar"

And, if we escape a quote with a backslash, nothing changes from the output above:

$ printf '"foo\"bar"' | xargs --null printf %s\\n
"foo"bar"

Note that the backslash is not printed. As far as I understand it, when a backslash scape escapes a character that is not treated in a special way, the escape does nothing.

And there is also --delimiter=delim:

Excerpt from man 1 xargs

-d delim
--delimiter=delim

  Input items are terminated by the specified character. The
  specified delimiter may be a single character, a C-style character
  escape such as \n, or an octal or hexadecimal escape code. Octal
  and hexadecimal escape codes are understood as for the printf
  command. Multibyte characters are not supported. When processing
  the input, quotes and backslash are not special; every character
  in the input is taken literally. The -d option disables any
  end-of-file string, which is treated like any other argument. You
  can use this option when the input consists of simply
  newline-separated items, although it is almost always better to
  design your program to use --null where this is possible.

So if we use --delimiter, “quotes and backslashes are not special; every character in the input is taken literally”:

$ printf '"foo\"bar"' | xargs -d \\0 printf %s\\n
"foo"bar"