linux下shell脚本学习

#!/bin/sh

#!/bin/sh


　　#对变量赋值：
　　a="hello world"
　　# 现在打印变量a的内容：
　　echo "A is:"
　　echo $a

3. Shell命令和流程控制

　#!/bin/sh
　　# The ticks are backticks (`) not normal quotes ():
tar -zcvf lastmod.tar.gz `find . -mtime -1 -type f -print`

#!/bin/sh


　　if [ "$SHELL" = "/bin/bash" ]; then
　　echo "your login shell is the bash (bourne again shell)"
　　else
　　echo "your login shell is not bash but $SHELL"
　　fi

#!/bin/sh


　　mailfolder=/var/spool/mail/james
　　[ -r "$mailfolder" ] { echo "Can not read $mailfolder"exit 1; }
　　echo "$mailfolder has mail from:"
　　grep "^From " $mailfolder

#!/bin/sh
　　ftype=`file "$1"`
　　case "$ftype" in
　　"$1: Zip archive"*)
　　unzip "$1"
　　"$1: gzip compressed"*)
　　gunzip "$1"
　　"$1: bzip2 compressed"*)
　　bunzip2 "$1"
　　*) error "File $1 can not be uncompressed with smartzip";;
　　esac

#!/bin/sh


　　echo "What is your favourite OS?"
　　select var in "Linux" "Gnu Hurd" "Free BSD" "Other"; do
　　break
　　done
　　echo "You have selected $var"

#!/bin/sh
　　for var in A B Cdo
　　echo "var is $var"
　　done

#!/bin/sh


　　# list a content summary of a number of RPM packages
　　# USAGE: showrpm rpmfile1 rpmfile2 ...
　　# EXAMPLE: showrpm /cdrom/RedHat/RPMS/*.rpm
　　for rpmpackage in $*; do
　　if [ -r "$rpmpackage" ];then
　　echo "=============== $rpmpackage =============="
　　rpm -qi -p $rpmpackage
　　else
　　echo "ERROR: cannot read file $rpmpackage"
　　fi
　　done

#!/bin/sh
　　echo *.jpg

#!/bin/sh
　　echo "*.jpg"
　　echo '*.jpg'

#!/bin/sh
　　echo $SHELL
　　echo "$SHELL"
　　echo '$SHELL'

#!/bin/sh


　　# we have less than 3 arguments. Print the help text:
　　if [ $# -lt 3 ]then
　　cat <<HELP
　　ren -- renames a number of files using sed regular expressions
　　USAGE: ren regexp replacement files...
　　EXAMPLE: rename all *.HTM files in *.html:
　　ren HTM$ html *.HTM
　　HELP
　　exit 0
　　fi
　　OLD="$1"
　　NEW="$2"
　　# The shift command removes one argument from the list of
　　# command line arguments.
　　shift
　　shift
　　# $* contains now all the files:
　　for file in $*; do
　　if [ -f "$file" ]then
　　newfile=`echo "$file" | sed "s/${OLD}/${NEW}/g"`
　　if [ -f "$newfile" ]; then
　　echo "ERROR: $newfile exists already"
　　else
　　echo "renaming $file to $newfile ..."
　　mv "$file" "$newfile"
　　fi
　　fi
　　done

#!/bin/sh
　　# vim: set sw=4 ts=4 et:
　　help()
　　{
　　　　cat <<HELP
　　　　xtitlebar -- change the name of an xterm, gnome-terminal or kde konsole
　　　　USAGE: xtitlebar [-h] "string_for_titelbar"
　　　　OPTIONS: -h help text
　　　　EXAMPLE: xtitlebar "cvs"
　　　　HELP
　　　　exit 0
　　}
　　# in case of error or if -h is given we call the function help:
　　[ -z "$1" ] && help
　　[ "$1" = "-h" ] && help
　　# send the escape sequence to change the xterm titelbar:
　　echo -e "33]0;$107"
　　#在脚本中提供帮助是一种很好的编程习惯，这样方便其他用户（和您）使用和理解脚本。

#!/bin/sh
　　help()
　　{
　　　　cat <<HELP
　　　　This is a generic command line parser demo.
　　　　USAGE EXAMPLE: cmdparser -l hello -f -- -somefile1 somefile2
　　　　HELP
　　　　exit 0
　　}
　　while [ -n "$1" ]; do
　　case $1 in
　　-h) help;shift 1;; # function help is called
　　-f) opt_f=1;shift 1;; # variable opt_f is set
　　-l) opt_l=$2;shift 2;; # -l takes an argument -> shift by 2
　　--) shift;break;; # end of options
　　-*) echo "error: no such option $1. -h for help";exit 1;;
　　*) break;;
　　esac
　　done
　　echo "opt_f is $opt_f"
　　echo "opt_l is $opt_l"
　　echo "first arg is $1"
　　echo "2nd arg is $2"

#!/bin/sh 
# vim: set sw=4 ts=4 et:
help()
{
    cat <<HELP
    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 <<HELP
    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 9 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

　　这将返回所有语法错误。

linux下shell脚本学习

原文：http://blog.csdn.net/whatday/article/details/50977529