1. Script- Are distinct from the core code of the application, which is usually written in a different language, and are often created or at least modified by the end-user. Scripts are often interpreted from source code or bytecode, whereas the applications they control are traditionally compiled to native machine code.
Program-The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, from which executable programs are derived (e.g., compiled). 2. tempfile=/tmp/$$.$script cp $editfile $tempfile if vim $editfile then mv $tempfile bak.$(basename $editfile) echo "$script: backup file created" else mv $tempfile editerr echo "$script: edit error--copy of " \ "original file is in editerr" 1>&2 fi. 3. $ function perms () {
> chmod u+x $1
> }
a. When you are writing many shell scripts, it can get tedious to give many chmod commands. This function speeds up the process.
b. $ function perms {
> chmod u+x $*
> }
c. Put the function in the ~/.bash_profile and/or ~/.bashrc file to make it available each time you log in (using bash).
d. Use source to execute the file you put the function in, for example,
$ source ~/.bash_profile

4. A shell function will do nothing unless it is explicitly called by other code, typically in a shell script. A shell script is a runnable, executable process, which can call other shell scripts and/or functions. The question might be worded backwards - it is necessary to write shell functions for shell scripts when certain logical functionality is required to be performed multiple times. Consider a shell function equivalent to a program subroutine - they operate the same way. "command prompt" (Microsoft), "shell" (Linux), or "terminal" (Unix/Linux) 5. while : do Time=’date +%r’ echo -n $Time
sleep