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linuxshellunixwhitespacexargs

Why does xargs -L yield the right format, while xargs -n doesn't?

Consider the following:

$ echo index.html* | xargs -L 1 ls -l
-rw-r--r-- 1 zeki zeki  17198 2011-05-03 23:18 index.html
-rw-r--r-- 1 zeki zeki  17198 2011-05-03 23:20 index.html.1
-rw-r--r-- 1 zeki zeki  17198 2011-05-03 23:21 index.html.2
-rw-r--r-- 1 zeki zeki 146589 2011-05-05 12:29 index.html.3
$ echo index.html* | xargs -n 1 ls -l
-rw-r--r-- 1 zeki zeki 17198 2011-05-03 23:18 index.html
-rw-r--r-- 1 zeki zeki 17198 2011-05-03 23:20 index.html.1
-rw-r--r-- 1 zeki zeki 17198 2011-05-03 23:21 index.html.2
-rw-r--r-- 1 zeki zeki 146589 2011-05-05 12:29 index.html.3

Why does the -n option yield an incorrect formatting? Just in case, I'm using bash under Ubuntu. Thanks.

Solution

  • -L splits by lines; echo doesn't separate its output by lines but by spaces, so a single ls -l is run and that formats all the columns as a group.

    -n splits by parameters; in the absence of -L or -0, the separator is whitespace (possibly modified by quoting), so each filename gets its own ls -l run and there is no way for the independent runs to coordinate column widths.