Shell command xargs & sed doesn't work

Question

I just want to batch modify the suffix of the files,but it doesn't work! The command line I used as below:

ls *html | xargs  -I{}  echo "\`echo {} |  sed 's/html/css/g'\`"

However, when I just used ls *html ,it shows:

file1.html  file2.html  file3.html  file4.html  file5.html

used ls *html | sed 's/html/css/g' ls *html | sed 's/html/css/g' ,it shows as I expected! like this:

file1.css file2.css file3.css file4.css file5.css

I work on Mac OS. Could anyone give me some suggestions? Thans in advance.

Answer 1

Because the backquotes are in double quotes, it gets executed immediately by the shell and not by xargs on each file.

The result is the same as

ls *html | xargs -I{} echo "{}"

However, if you use single quotes, you run into other troubles. You end up having to do something like this:

ls *html | xargs -I{} sh -c 'echo `echo {} | sed '\''s/html/css/g'\''`'

but it gets to be a mess, and we haven't even got to the actual renaming yet.

Using a loop is a bit nicer:

for file in *html; do
  newname=${file%html}css
  mv "$file" "$newname"
done

Answer 2

使用GNU并行：

ls *html | parallel echo before {} after {.}.css