unix commands about executable file -

unix commands about executable file -

in unix pc computer there directory has excetuable programme example. if while within directory , tried above commands:

> illustration example: command not found >./example hello world! >

1)why programme did not run @ first time? 2)why programme run sec time? 3)what needs first seek programme run successfully?

and 1 question different above command in unix operation scheme can check size of file named example11?

read documentation of bash(1), intro(1), ls(1), stat(1), strace(1), execve(2), stat(2), intro(2), execvp(3), hier(7), environ(7)

most shells (notably bash) using path environment variable find executables. command not found message after failure of execvp in shell (or more because shell did not found file executable pass execve after fork(2)).

consider editing ~/.bashrc file if want alter (i.e. set path).

read advanced linux programming & advanced bash scripting guide. btw, gnu bash free software, study source code.

type /bin/ls --help or ls --help. seek ls -l example1 list file named example1

read globbing, e.g. glob(7). seek ls -l exampl* understand first shell expanding exampl* before passing arguments /bin/ls

unix executable