Shell gets the current path

Prg= "$"while do  ls= ' ls-ld ' $PRG "'  link= ' expr ' $ls": ' .*-> \ (. *\) $ ' `   if expr "$link": '/.* ' >/dev/null; then    PRG= "$link"  else C15/>PRG= ' dirname ' $PRG '/' $link '  fidoneprgdir= ' dirname ' $PRG '-Z ' $CATALINA _home "] && catalina_home= ' CD $PRGDIR/:" >/dev/null"Catalina_home is $CATALINA _home";

#此处的RPG抓取的是文件名, because it could be a symbolic link, the function of a looping statement is to find the file's true source path
-H is used to determine if the $prg file exists and is a symbolic link
Ls-ld "$PRG" to view the details of the current directory of the running program, but only the directory, excluding subdirectories and files under the directory

link= ' expr ' $ls ': ' .*-> \ (. *\) $ '
Expr means to match a string to a pattern and return the string to which it is matched
Or calculate the number of characters to match according to a pattern. Commonly used: expr value:expression


The "$ls" represents the contents of the variable ls.


' .*-> \ (. *\) $ ' This part is a regular expression,. * Part denotes any character, and is the actual two characters, the soft link in Linux will use the Ls-al command to list the file, with "soft link-to-real file" way to show the soft link and The actual file to which it is linked. The $ here represents the end of the line \ (that is, because (the shell belongs to a special symbol, you need to use escape; \) is also escaped as);

The entire ' expr ' $ls ': ' .*-> \ (. *\) $ ' means the actual file or the real directory to which the soft connection was taken.

[ -z "$CATALINA_HOME" ] && CATALINA_HOME=`cd"$PRGDIR/..">/dev/null; pwd` 判断变量$CATALINA_HOME是否存在，不存在则给予附值

Shell gets the current path