<![CDATA[向东博客 专注WEB应用 构架之美 --- 构架之美，在于尽态极妍 | 应用之美，在于药到病除]]> https://jackxiang.com/index.php zh-cn https://jackxiang.com/post// <![CDATA[[实践OK]shell函数以及函数失败返回的写法，常用的shell判断语句及常用shell函数]]> jack <xdy108@126.com> Thu, 14 Jan 2010 05:17:47 +0000 https://jackxiang.com/post// cat fun.sh


sh fun.sh
hello world...\n
ls: cannot access /tmp2: No such file or directory
ls /tmp2 failed


今天重新再翻看了一下shell程序相关的资料。准备重新将shell再提高一下。
将http://seo-dic.com.cn/archives/2496 提到的《Advanced Bash-Scripting Guide》《高级bash脚本编程指南》上附带的源码重新再看一次。
为了方便查看。我将所有的源代码全部导到一个文件中，再一一查看。省去了每次只打开一个脚本的麻烦。同时，将几个经常用的shell脚本函数稍做了下列举。希望后面可以用得到。
find -type f -name "*.sh" -exec cat {} >>sh.all \;

检查目录是否存在，若不存在，则创建相应目录。


# Check for and create datadir if necessary:
if test ! -d $datadir
        then
        mkdir $datadir
fi


shell参数判断，若不符合则显示使用方式及退出。

E_BADARGS=65

case $# in
  0|1)             # The vertical bar means "or" in this context.
  echo "Usage: `basename $0` old_file_suffix new_file_suffix"
  exit $E_BADARGS  # If 0 or 1 arg, then bail out.
  ;;
esac

另例：

E_OPTERR=65

if [ "$#" -eq 0 ]
then   # Script needs at least one command-line argument.
  echo "Usage $0 -[options a,b,c]"
  exit $E_OPTERR
fi


检查是用户是否是root权限的方式：


ROOT_UID=0         # Root has $UID 0.
E_WRONG_USER=65    # Not root?

E_NOSUCHUSER=70
SUCCESS=0


if [ "$UID" -ne "$ROOT_UID" ]
then
  echo; echo "Only root can run this script."; echo
  exit $E_WRONG_USER
else
  echo
  echo "You should know better than to run this script, root."
  echo "Even root users get the blues... "
  echo
fi

进行用户目录判断：
LOG_DIR=/var/log
ROOT_UID=0     # Only users with $UID 0 have root privileges.
LINES=50       # Default number of lines saved.
E_XCD=66       # Can't change directory?
E_NOTROOT=67   # Non-root exit error.

cd $LOG_DIR

if [ `pwd` != "$LOG_DIR" ]  # or   if [ "$PWD" != "$LOG_DIR" ]
                            # Not in /var/log?
then
  echo "Can't change to $LOG_DIR."
  exit $E_XCD
fi  # Doublecheck if in right directory, before messing with log file.
]]> https://jackxiang.com/post//#blogcomment <![CDATA[[评论] [实践OK]shell函数以及函数失败返回的写法，常用的shell判断语句及常用shell函数]]> <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 https://jackxiang.com/post//#blogcomment