Using Regex groups in bash

Greetings,

I've got a directory with a list of pdfs in it:

file1.pdf, file2.pdf, morestuff.pdf ... etc.

I want to convert these pdfs to pngs, ie

file1.png, file2.png, morestuff.png ... etc.

The basic command is,

convert from to,

But I'm having trouble getting convert to rename to the same file name. The obvious 'I wish it worked this way' is

convert *.pdf *.png

But clearly that doesn't work. My thought process is that I should utilize regular expression grouping here, to say somethink like

convert (*).pdf %1.png

but that开发者_StackOverflow社区 clearly isn't the right syntax. I'm wondering what the correct syntax is, and whether there's a better approach (that doesn't require jumping into perl or python) that I'm ignoring.

Thanks!

for files in *.pdf 
do  
   if [ -f "$files" ];then
      convert "$files" "${files%.pdf}.png"
   fi
done

if you need to do it recursively,

find /path -type f -iname "*.pdf" | while read -r FILE
do
   convert "$FILE" "${FILE%.pdf}.png"
done

If you really wanted to use regex, Bash≥3.1 supports regular expressions.

for f in *.pdf; do
    [[ $f =~ ^(.*)\.pdf$ ]] &&
    convert "$f" "${BASH_REMATCH[1]}.png"
done

And all systems should have the shell utility expr.

for f in *.pdf; do
    match=$(expr "$f" : '\(.*\)\.pdf$') &&
    convert "$f" "$match.png"
done

But Bash's parameter expansion (as demonstrated in the other answers) works better for simple cases like this.

for f in *.pdf
do
  convert "$f" "${f%.pdf}.png"
done

ls *.pdf | sed 's/\"/\\"/;s/^\(.*\).pdf$/convert "&" "\1.png"/' | bash