Question about text manipulation (substitution) using expr/egrep/awk in Bash

[acwbrat]

Hey!

I am new to this forum but confused in programming to Bash scripting. How do change the file extension using awk and expr (or egrep).

Ex: me.mp3 to me.wav

I have tried:

files=$(ls -1 | grep *.mp3)

for x in $files
do
mv $x band_song$x
done

This example only changes the file name and not the extention.

[papetova]

You could do something like:

for i in `ls -1 *.mp3| awk -F. '{print $1}'`; do mv $i.mp3 $i.wav; done

Of course there are a million other ways and probably better ones too, but this way works also.

[acwbrat]

I want to use expr in order to change a the file extension from .mp3 to .wav. I wasn't able to find any examples in Google.

I know the more simple codes are a lot better than complex codes.

[radoulov]

I want to use expr in order to change a the file extension from .mp3 to .wav. I wasn't able to find any examples in Google.
[...]

Why expr?

A few ways (without expr, awk etc.):

$ touch {1..5}.mp3
$ ls
1.mp3  2.mp3  3.mp3  4.mp3  5.mp3
$ rename s/.mp3/.wav/ *mp3
$ ls
1.wav  2.wav  3.wav  4.wav  5.wav

$ ls
1.mp3  2.mp3  3.mp3  4.mp3  5.mp3
$ for f in *.mp3;do mv "$f" "${f%.*}".wav;done
$ ls
1.wav  2.wav  3.wav  4.wav  5.wav

With zsh:

% ls
1.mp3  2.mp3  3.mp3  4.mp3  5.mp3
% autoload -U zmv
% zmv -W '*.mp3' '*.wav'
% ls
1.wav  2.wav  3.wav  4.wav  5.wav

[acwbrat]

I have this code:

#!/bin/bash
#
# Replaces blanks with underscores in all the filenames
# of the current directory.

i=0

for filename in *
do
echo "$filename" | grep -q " "
if [ $? -eq 0 ]
then
fname=$filename
n=`echo $fname | sed -e "s/ /_/g"`
mv "$fname" "$n"
((i++1))
fi
done

echo "$i file(s), done."
exit 0

When I tried to substitute my information, it didn't compute.

[ghostdog74]

I have this code:

#!/bin/bash
#
# Replaces blanks with underscores in all the filenames
# of the current directory.

i=0

for filename in *
do
echo "$filename" | grep -q " "
if [ $? -eq 0 ]
then
fname=$filename
n=`echo $fname | sed -e "s/ /_/g"`
mv "$fname" "$n"
((i++1))
fi
done

echo "$i file(s), done."
exit 0

When I tried to substitute my information, it didn't compute.

you are trying to increment i, it should be like this

i=$(($i+1))

[radoulov]

you are trying to increment i, it should be like this

i=$(($i+1))

With recent versions of bash(and, of course, zsh):

$((++i))