Replace output file extension in linux shell command

Question

Say I have a command, convertImage, which takes some input jpeg, and spits out a new png in the same directory:

convertImage --format png photo.jpg -o photo.png

I want to make an alias "convertToPng" which takes only one arg, the file:

convertToPng photo.jpg

My current solution is this:

alias convertToPng "convertImage --format png \!:1 -o \!:1.png"

However this will name the output file to "photo.jpg.png" and I want it to be named "photo.png". Is there any way to parse the filename first, and then pass that to the convertImage executable?

Answer 1

If your input is always jpg then

convertToPng photo
alias convertToPng "convertImage --format png \!:1.jpg -o \!:1.png"

or give extension as 2nd parameter

convertToPng photo jpg
alias convertToPng "convertImage --format png \!:1.\!:2 -o \!:1.png"

or last option

convertToPng photo.jpg
alias convertToPng "convertImage --format png \!:1 -o `echo $1 | cut -f1 -d'.'`.png"

or write a function in your .bashrc as follows

function convert() 
{
    convertImage --format png $1 -o `echo $1 | cut -f1 -d'.'`.png;
}

and execute above function as

convert photo.jpg

I prefer the function way as it gives you lot flexibility over aliases and you can do much more than just one statement.

Answer 2

echo photo.jpg | awk -F. '{print $1".png"}'

可以在命令行调用中使用它，如下所示：

$ convertImage --format png photo.jpg -o `echo photo.jpg | awk -F. '{print $1".png"}'`