* 用shell 批次改檔名
   * 此用法應用到 for in , 正規表示法, awk , sed 因此還學滿多的
{{{
#!/bin/sh
cd ~/test2
echo `pwd`
for i in *.[tT][iI][fF]; do
        #若目錄內無 .tif 檔案 $i 會傳回 "*.[tT][iI][fF]"
        if [ "$i" != "*.[tT][iI][fF]" ]; then
                #取得副檔名
                subname="`echo $i | awk -F '.' '{print $NF}'`"
                #取得主檔名
                filename="`echo $i | sed -e s/\.${subname}//`"
                #將 .tif 轉成 .pdf
                #tiff2pdf -o "${filename}.pdf" "$i"
                echo "tif -> pdf"
                mv ${filename}.${subname} ${filename}.pdf
                #若執行成功則刪除 .tif 檔案
                if [ $? -eq 0 ]; then
                        rm -rf $i
                fi
        fi
done
}}}

 * awk 
{{{
Examples:
	gawk '{ sum += $1 }; END { print sum }' file
	gawk -F: '{ print $1 }' /etc/passwd
}}}

 * sed 
{{{
Usage: sed [OPTION]... {script-only-if-no-other-script} [input-file]...
  -n, --quiet, --silent
                suppress automatic printing of pattern space
  -e script, --expression=script
                 add the script to the commands to be executed
}}}