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shift命令
向腳本傳遞參數時，有時需要將每一個參數偏移以處理選項，這就是 shift命令的功能。它每次將參數位置向左偏移一位，下面用一段簡單腳本詳述其功能。腳本使用 while循環反饋所有傳遞到腳本的參數。使用shift命令來處理傳遞到腳本的每一個參數：

#!/bin/sh
loop=0
while [ $# -ne 0 ]
do
echo $1
shift
done

使用shift處理文件大小寫轉換

!#/bin/sh
# tr_case
# convert files to either  upper or lower case
FILES=""
TRCASE=""
EXT=""
OPT=no
# gets called when a conversion fails
error_msg()
{
_FILENAME=$1
echo "`basename $0`: Error the conversion failed on $_FILENAME"
}
if [ $# -eq 0 ]
then
echo "For more info try `basename $0` --help"
exit 1
fi
while [ $# -gt 0 ]
do
case $1 in
#set the variables based on what option was used
-u)TRCASE=upper
EXT=".UC"
OPT=yes
shift
;;
-l)TRCASE=lower
EXT=".LC"
OPT=yes
shift
;;
-help) echo "convert a file(s) to uppercase from lowercase"
echo "convert a file(s) from lowercase to uppercase"
echo "will convert all characters according to the sepcified command option."
echo "where option is"
echo "-l Convert to lowercase"
echo "-u Convert to uppercase"
echo "The original file(s) is not touched. A new file(s)"
echo "will be created with either a .UC or .LC extension"
echo "usage: $0 -[l|u] file [file..]"
exit 0
;;
-*) echo "usage: `basename $0` -[l|u] file [file..]"
exit 1
;;
*) # collect the files to process
if [ -f $1 ]
then
# add the filenames to a variable list
FILES=$FILES" "$1
else
echo "`basename $0` : Error cannot find the file $1"
fi
shift
;;
esac
done
if [ "$OPT" = "no" ]
then
echo "`basename $0`: Error you need to specify an option. No action taken"
echo "`basename` --help"
exit 1
fi
# now read in all the file(s)
# use the variable LOOP, I just love the word LOOP
for LOOP in $FILES
do
case $TRCASE in
lower) cat $LOOP|tr "[a-z]" "[A-Z]" >$LOOP$EXT
if [ $? != 0 ]
then
error_msg $LOOP
else
echo "Converted file called $LOOP$EXT"
fi
;;
upper) cat $LOOP|tr "[A-Z]" "[a-z]" > $LOOP$EXT
if [ $? != 0 ]
then
error_msg $LOOP
else
echo "Converted file called $LOOP$EXT"
fi
;;
esac
done

getopts命令

#!/bin/sh
#getopts1
#set the vars
ALL=false
HELP=false
FILE=false
VERBROSE=false
while getopts ahfgv OPTION
do
case $OPTION in
a)ALL=true
echo "ALL is $ALL"
;;
h)HELP=true
echo "HELP is $HELP"
;;
f)FILE=true
echo "FILE is $FILE"
;;
v)VERBOSE=true
echo "VERROSE is $VERROSE"
;;
esac
done

/home/l/g/tomotoboy/getopts >getopts1 -a
ALL is true
/home/l/g/tomotoboy/getopts >getopts1 -v
VERROSE is
/home/l/g/tomotoboy/getopts >getopts1 -v -a -h
VERROSE is
ALL is true
HELP is true

getopts一般格式為：
getopts  option_string variable
在上述例子中使用腳本：
while getopts ahfgv OPTION
可以看出while循環用于讀取命令行，option_string為指定的5個選項（- a，- h，- f，- g，- v）,腳本中variable為OPTION。注意這里并沒有用連字符指定每一單個選項。

使用getopts指定變量取值
有時有必要在腳本中指定命令行選項取值。getopts為此提供了一種方式，即在option_string中將一個冒號放在選項后。例如：
getopts ahfvc: OPTION
上面一行腳本指出，選項 a、h、f、v可以不加實際值進行傳遞，而選項 c必須取值。使用選項取值時，必須使用變量 OPTARG保存該值。如果試圖不取值傳遞此選項，會返回一個錯誤信息。錯誤信息提示并不明確，因此可以用自己的反饋信息屏蔽它，方法如下：
將冒號放在option_string開始部分。

while getopts :ahfgvc:  OPTION

#!/bin/sh
#getopts1
#set the vars
ALL=false
HELP=false
FILE=false
VERBROSE=false
COPIES=0 #the value for the -c option is set to zero
while getopts :ahfgvc: OPTION
do
case $OPTION in
a)ALL=true
echo "ALL is $ALL"
;;
h)HELP=true
echo "HELP is $HELP"
;;
f)FILE=true
echo "FILE is $FILE"
;;
v)VERBOSE=true
echo "VERROSE is $VERROSE"
;;
c)COPIES=$OPTARG
echo "COPIES is $COPIES"
;;
\?) #usage stagement
echo "`basename $0` -[a h f v] -[c value] file" >&2
;;
esac
done  

/home/l/g/tomotoboy/getopts >chmod 755 getopts2
/home/l/g/tomotoboy/getopts >getopts2 -c hello
COPIES is hello
/home/l/g/tomotoboy/getopts >getopts2 -h -c hello
HELP is true
COPIES is hello

訪問取值方式
getopts的一種功能是運行后臺腳本。這樣可以使用戶加入選項，指定不同的磁帶設備以備份數據。使用getopts實現此任務的基本框架如下：