cvt.sh

Shall高级编程

#!/bin/bash
#  cvt.sh:
#  Converts all the MacPaint image files in a directory to "pbm" format.

#  Uses the "macptopbm" binary from the "netpbm" package,
#+ which is maintained by Brian Henderson ([e-mail]).
#  Netpbm is a standard part of most Linux distros.

OPERATION=macptopbm
SUFFIX=pbm          # New filename suffix. 

if [ -n "$1" ]
then
  directory=$1      # If directory name given as a script argument...
else
  directory=$PWD    # Otherwise use current working directory.
fi  
  
#  Assumes all files in the target directory are MacPaint image files,
#+ with a ".mac" filename suffix.

for file in $directory/*    # Filename globbing.
do
  filename=${file%.*c}      #  Strip ".mac" suffix off filename
                            #+ ('.*c' matches everything
			    #+ between '.' and 'c', inclusive).
  $OPERATION $file > "$filename.$SUFFIX"
                            # Redirect conversion to new filename.
  rm -f $file               # Delete original files after converting.   
  echo "$filename.$SUFFIX"  # Log what is happening to stdout.
done

exit 0

# Exercise:
# --------
#  As it stands, this script converts *all* the files in the current
#+ working directory.
#  Modify it to work *only* on files with a ".mac" suffix.