CODEWITHSUNDEEP
bashshellexec
user1604294
user1604294

Reputation:

How to exec bash script w/o exiting shell

I want to execute a bash script in the current shell, not a subshell/subprocess. I believe using exec allows you to do that. But if I run:

exec ./my_script.sh

the shell will exit and it will say "process completed". Is there a way to execute a script in the same shell somehow w/o exiting the process.

note the only thing my_script.sh does is:

export foo=bar

but if there was some error in my script, it didn't appear in the console.

Upvotes: 0

Views: 4046

Answers (3)

Gopika BG
Gopika BG

Reputation: 817

man page says:-

exec [-cl] [-a name] [command [arguments]] If command is specified, it replaces the shell. No new process is created. The arguments become the arguments to command. If the -l option is supplied, the shell places a dash at the beginning of the zeroth argument passed to command.This is what login(1) does. The -c option causes command to be executed with an empty environment.

if you want to execute a bash script in the current shell,you can try

bash my_script.sh or ./my_script.sh

Upvotes: 0

Stephen C
Stephen C

Reputation: 718788

As @Snakienn has said, you can / should use the "." builtin command to "source" the file containing commands; e.g.

 . ./my_script.sh

What this does is to temporarily change where the shell is reading commands from. Commands and other shell input are read from the file as if they were being read from the terminal. When the shell gets to the end-of-file, it switches back to taking input from the console.

This is called "sourcing". (Not "execing".) And indeed the shell accepts source as an alternative name for the . command.

The exec command does something completely different. As the bash manual entry says:

 exec [-cl] [-a name] [command [arguments]]

If command is specified, it replaces the shell. No new process is created. The arguments become the arguments to command.

The concept and terminology of exec comes from early UNIX (i.e Unix V6 or earlier) where the syscalls for running a child command were fork and exec. The procedure was:

  • fork the current process creating a clone of current process (the child)
  • in the child process exec the new command
  • in the parent process, wait for the child process to complete

Upvotes: 3

Snakienn
Snakienn

Reputation: 619

you can try . ./my_script.sh.

The first dot stands for the current shell.

Upvotes: 1

Related Questions