两个很详细的shell 实例代码

#!/bin/sh
# vim: set sw=4 ts=4 et:
help()
{
　cat < b2h -- convert binary to decimal
USAGE: b2h [-h] binarynum
OPTIONS: -h help text
EXAMPLE: b2h 111010
will return 58
HELP
　exit 0
}
error()
{
　　# print an error and exit
　　echo "$1"
　　exit 1
}
lastchar()
{
　　# return the last character of a string in $rval
　　if [ -z "$1" ]; then
　　　　# empty string
　　　　rval=""
　　　　return
　　fi
　　# wc puts some space behind the output this is why we need sed:
　　numofchar=`echo -n "$1" | wc -c | sed 's/ //g' `
　　# now cut out the last char
　　rval=`echo -n "$1" | cut -b $numofchar`
}
chop()
{
　　# remove the last character in string and return it in $rval
　　if [ -z "$1" ]; then
　　　　# empty string
　　　　rval=""
　　　　return
　　fi
　　# wc puts some space behind the output this is why we need sed:
　　numofchar=`echo -n "$1" | wc -c | sed 's/ //g' `
　　if [ "$numofchar" = "1" ]; then
　　　　# only one char in string
　　　　rval=""
　　　　return
　　fi
　　numofcharminus1=`expr $numofchar "-" 1`
　　# now cut all but the last char:
　　rval=`echo -n "$1" | cut -b 0-${numofcharminus1}`
}
while [ -n "$1" ]; do
case $1 in
　　-h) help;shift 1;; # function help is called
　　--) shift;break;; # end of options
　　-*) error "error: no such option $1. -h for help";;
　　*) break;;
esac
done
# The main program
sum=0
weight=1
# one arg must be given:
[ -z "$1" ] && help
binnum="$1"
binnumorig="$1"
while [ -n "$binnum" ]; do
　　lastchar "$binnum"
　　if [ "$rval" = "1" ]; then
　　　　sum=`expr "$weight" "+" "$sum"`
　　fi
　　# remove the last position in $binnum
　　chop "$binnum"
　　binnum="$rval"
　　weight=`expr "$weight" "*" 2`
done
echo "binary $binnumorig is decimal $sum"
#

#!/bin/sh
# vim: set sw=4 ts=4 et:
ver="0.1"
help()
{
　　cat < rotatefile -- rotate the file name
USAGE: rotatefile [-h] filename
OPTIONS: -h help text
EXAMPLE: rotatefile out
This will e.g rename out.2 to out.3, out.1 to out.2, out to out.1
and create an empty out-file
The max number is 10
version $ver
HELP
　　exit 0
}
error()
{
　　echo "$1"
　　exit 1
}
while [ -n "$1" ]; do
case $1 in
　　-h) help;shift 1;;
　　--) break;;
　　-*) echo "error: no such option $1. -h for help";exit 1;;
　　*) break;;
esac
done
# input check:
if [ -z "$1" ] ; then
error "ERROR: you must specify a file, use -h for help"
fi
filen="$1"
# rename any .1 , .2 etc file:
for n in Array 8 7 6 5 4 3 2 1; do
　　if [ -f "$filen.$n" ]; then
　　　　p=`expr $n + 1`
　　　　echo "mv $filen.$n $filen.$p"
　　　　mv $filen.$n $filen.$p
　　fi
done
# rename the original file:
if [ -f "$filen" ]; then
　　echo "mv $filen $filen.1"
　　mv $filen $filen.1
fi
echo touch $filen
touch $filen