| From: Stewart C. Russell via talk <talk@gtalug.org> | On 2018-05-31 03:00 PM, Stewart Russell wrote: | > | > convert file.{png,jpg} | > | > and bash will do the magic. What I don't know is if that will accept a | > glob. | | narrator voice: it didn't accept a glob. | | (that is, | | convert *.{png,jpg} | | does *something*, but neither what you'd expect nor want) Image Magick's convert command sure is magic. But its syntax does not follow UNIX conventions. SYNOPSIS convert [input-option] input-file [output-option] output-file "accept a glob" is not a UNIX thing. globbing is done by the shell. What you mean is: accepts a sequence of pathnames on the command line, often denoted "file..." in a synopsis. Like this SYNOPSIS cat [OPTION]... [FILE]... The convert synopsis is actually wrong, I think. I think that it should be convert [input-option]... input-file [output-option]... output-file What you wanted to do is actually more awkward in UNIX than in systems where the globbing is done by the program (I think). In those systems, the "filename extension" is a first-class notion. for i in *.png ; do convert "$i" "$(basename "$i" .png).jpg" ; done I don't even understand why the inner quotes don't need to be escaped. I tested it with this simulation: for i in "hello.png" "good bye.png" ; do echo convert "$i" "$(basename "$i" .png).jpg" ; done basename strips any directory prefix off of its argument but I didn't worry because *.png won't produce paths with directory prefixes. Beware if you try to generalize this code. bash has powerful but odd macro substitution operators. Here's a version of the code where the basename has been replaced by one of these operator. I have no idea if this works in other shells for i in *.png ; do convert "$i" "${i%.png}.jpg" ; done (I learned the Bourne shell in the 1970's and usually stick to that original simple language. I have to read bash(1) to find things like this.)