Generating the output file name from the input file in bash

Question

I have a bash script:

#!/bin/bash
convert "$1" -resize 50% "$2"

Instead of passing two arguments while the script is run I want to mention just the source (or input file name) and the output file name should be auto-genarated from the source file name. Something like this "$1" | cut -d'.' -f1".jpg". If the input file name was myimage.png, the output name should be myimage.jpg. .jpg should be appended to the fist part of the source file name. It should also work if the argument is: *.png. So how can I modify my script?

Does this work at the comand line: convert "*.png" -resize 50% "*.jpg" ?? I suspect you'll need a loop in that case. — glenn jackman
– glenn jackman, Commented Mar 30, 2011 at 12:15

camh · Accepted Answer · 2011-03-30 09:45:07Z

5

The expansion ${X%pattern} removes pattern of the end of $X.

convert "$1" -resize 50% "${1%.*}.jpg"

To work on multiple files:

for filename ; do
    convert "$filename" -resize 50% "${filename%.*}.jpg"
done

This will iterate over each of the command line arguments and is shorthand for for filename in "$@". You do not need to worry about checking whether the argument is *.png - the shell will expand that for you - you will simple receive the expanded list of filenames.

edited Mar 30, 2011 at 9:45

answered Mar 30, 2011 at 7:59

camh

42.9k13 gold badges66 silver badges73 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

l0b0 · Accepted Answer · 2011-03-30 08:13:36Z

2

convert "$1" -resize 50% "${1%.*}.jpg"

The magic is in the %.* part, which removes everything after the last dot. If your file is missing an extension, it will still work (as long as you don't have a dot anywhere else in the path).

answered Mar 30, 2011 at 8:13

l0b0

59.6k32 gold badges155 silver badges247 bronze badges

Comments

Benoit Thiery · Accepted Answer · 2011-03-30 07:47:37Z

0

OUTFILE=`echo $1|sed 's/\(.*\)\..*/\1/'`.jpg
convert "$1" -resize 50% "$OUTFILE"

answered Mar 30, 2011 at 7:47

Benoit Thiery

6,4174 gold badges25 silver badges28 bronze badges

1 Comment

SiegeX Over a year ago

consider using $() instead of backticks

Collectives™ on Stack Overflow

Generating the output file name from the input file in bash

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related