. ${0%${0##*/}}Script_Name

if i issue this command, it is executing the script. can any one tell what is the meaning of ${0%${0##*/}}

man <your shell>

That's a sequence of two variable substitutions.

${var##string} returns $var with the longest possible prefix matching string removed

${var%string} returns $var with the shortest possible suffix matching string removed

Combined, these return the path name component from $0 which is the name of the currently running script. In other words, the construct attempts to find the file Script_Name from the same directory where the current script is running from, and execute it using the shell's source (dot) command. This is a common technique for including a snippet of shared code from another file into a shell script.

Thanks... That was really very helpful... I came to know the meaning of ${var##string} and ${var%string}.

if i am in some XYZ dir. I have 2 scripts, Script1 and Script2 in it.

To call Script2 from Script1, I can use

. ${0%${0##*/}}Script2 or . ./Script2

Both do the same job. then why use this ". ${0%${0##*/}}Script2" instead of simply using ". ./Script2"?

$ temp=/u/ppattusa/unix
$ echo ${temp%${temp##*/}}
 
OUTPUT
/u/ppattusa/

In this case they expand to the same value, but that has not always to be the case. Suppose the following: you call your script not from the directory where it is stored but from somewhere else:

$ cd /some/dir
$ /some/other/dir/script
$ _

. ./script2

scripts adminBuildDomain and crstEnv are in the same directory. from this directory only we run all the scripts.

adminBuildDomain calls crstEnv

Code in adminBuildDomain is: . ${0%${0##*/}}crstEnv

${0%${0##*/}}crstEnv returns crstEnv value

since the directory path where we run the scripts is same as the directory where the scripts are present, we can use . ./crstEnv instead of . ${0%${0##*/}}crstEnv

i really dont understand the importance of ". ${0%${0##*/}}crstEnv" in this case. i dont understand why ". ${0%${0##*/}}crstEnv" is used instead of ". ./crstEnv"