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What does exec do in a shell script?
exec command in Linux is used to execute a command from the bash itself. This command does not create a new process it just replaces the bash with the command to be executed. If the exec command is successful, it does not return to the calling process.
What happens if you run exec ls in a UNIX shell why?
If you run ls , your shell process will start up another process to run the ls program, then it will wait for it to finish. When it finishes, control is returned to the shell.
What happens when you enter ls?
It is the way a user talks to the kernel, by typing commands into the command line (why it’s known as the command line interpreter). On the superficial level, typing ls -l displays all the files and directories in the current working directory, along with respective permissions, owners, and created date and time.
What happens when you use Exec in Bash?
Whenever we run any command in a Bash shell, a subshell is created by default, and a new child process is spawned (forked) to execute the command. When using exec, however, the command following exec replaces the current shell. This means no subshell is created and the current process is replaced with this new command.
Are there executables outside of the bash script?
Depending on the designation and version number of your bash interpreter some commands may not be available. External commands are executables accessible outside of a bash script like curl. Unlike functions, external commands are not stored as variables. The lower the precedence of a command type, the later the command may be interpreted.
When to use SSH to execute Linux command?
This is quite a common task for Linux system administrators, when it is needed to execute some command or a local Bash script from a one Linux workstation or a server on another remote Linux machine over SSH.
Which is the shell script used in Linux?
The majority of shell scripting done on Linux involve the bash shell. However, power users who have specified choices often use other shells such as Zsh and Ksh. We’ll mostly stick with Linux bash scripts in our examples due to their widespread popularity and immense usability.