improving shell algorithm

Question

I need to write a shell script.

-for example

my files:

daily.gfr.gif, abc.gif , def.gif , fgr.gif , fgt.gif , current.abc.gif

I want to change as below:

1_daily.gfr.tlf , 2_abc.tlf , 3_def.tlf , 4_fgr.tlf , 5_fgt.tlf , 6_current.abc.tlf

I write a script:

for file in *.gif
do
    filename=$(basename "$file")
    filename=${filename%.*}
    convert $file $filename.tlf
done

Is this right in your opinion? How can I add name changing?

Notes: (1) The names are listed in a different order than will be generated by *.gif; the names will be generated in alphabetic order. (2) The basename operation does nothing. You could have written filename=$(basename "$file" .gif) to remove the suffix, or you can do what you do on the next line. (3) You need a counter and an increment operation: counter=1 outside the loop, ${counter}_$filename.tlf as the second argument to convert, and ((counter++)) or similar to increment the counter. — Jonathan Leffler
– Jonathan Leffler, Commented Oct 12, 2013 at 23:10
Please don't deface your questions after people have taken the time to answer them. This isn't fair to people trying to answer you. — Brad Larson
– Brad Larson, Commented Oct 15, 2013 at 1:07

Alexander Vogt · Accepted Answer · 2013-10-20 08:28:55Z

3

nr=0
for file in *.gif; do
    nr=$(($nr+1))
    filename="$(basename "$file")"
    filename="${filename%.*}"
    convert "$file" "${nr}_$filename.tlf"
done

edited Oct 20, 2013 at 8:28

answered Oct 12, 2013 at 21:53

Alexander Vogt

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1 Comment

kojiro Over a year ago

Don't forget the quotes.

kojiro · Accepted Answer · 2013-10-12 22:17:49Z

1

If you're going to use the basename command instead of parameter expansions, you should use it to its fullest power by giving it an extension suffix to drop. That will take care of both birds with one stone.

nr=0
for file in *.gif; do
  filename="$(( ++nr ))_$(basename "$file" .gif).tlf"
  convert "$file" "$filename"
done

You could also do the whole thing with parameter expansion:

nr=0
for file in *.gif; do
  filename="$(( ++nr ))_${file##*/}"
  filename="${filename%.*}"
  convert "$file" "$filename"
done

The benefit of the parameter expansions is that you don't invoke a subshell every iteration. Unless you need to process a lot of files, it won't make a difference.

answered Oct 12, 2013 at 22:17

kojiro

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