新手看linux的启动脚本,有几句不明白,帮忙看看

feixiang151

if [ -f /etc/sysconfig/desktop ]; then
  . /etc/sysconfig/desktop             //. 后面有个空格,这句是什么意思啊

if [ -n "$PREFERRED" ] && which $PREFERRED >/dev/null 2>&1;then
  PREFERRED='which $PREFERRED'     //which在这里有什么用呢
  exec $PREFERRED    工艺    //直接exec startkde 不行吗

while [ x"$1" != x]; do    //这句又不明白了,x是干吗用的,整句又是什么意思呢

yongjian

well... you really need to learn some basic shell programming knowledge. Please read the top threads in the forum and also the well-known abs book. All your questions are in those places.

feixiang151

我也知道应该找本书好好从头开始看起.但现在急用,来不急这么仔细的看
希望各位能不嫌问题过分简单,给我个解答吧

yongjian

haha.. ok. promise me you will read the doc, ok.
1. '.' with a space means source the file. All the params and funcs defined in the target script will be sourced into the current running shell.
2. which is a program to find the absolute path of another program. say 'which ls' will show '/bin/ls'. Its much safer to use absolute path when referencing to a program.
3. [ x"$1" = x ] is a technic to verify if $1 is an empty string or not. It is only true when $1 is empty, not even $1 = " " (a single space. you don't see it but its not empty now.) ..

feixiang151

谢谢版主,正在看<<Learning the bash shell>>
1.变量和函数引进后是不是说当前脚本就可以完全使用它们？
２．&& which $PREFERRED >/dev/null 2>&1；这个条件测试有什么作用呢？我的理解是它把所有输出都重定向到/dev/null了．
３．明白了

yongjian

1. yes.
2. make sure there is a such program there and the test doesn't need to output the content of 'which $PREFERRED'.

feixiang151

呵，明白了，多谢！！
可否问一下，版主怎么总是用英文回答

yongjian

no Chinese configured in my laptop which is from my company...

skinny8306

it's so funny

kuroroluxlu

怎么回帖子的说的是英文？