ShellScript Issue Linux [closed] - linux

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Task 1:
If the Time is AM, print "It is Morning". If it is PM, print "It is not morning".
Task 2:
Given 2 arguments passed to the script.
Validate that 2 arguments have been submitted. If three arguments have not been provided, print "Must Supply 2 Arguments" and exit the script
Argument 1: Should be a directory (needs validated). If this does not exist, print "Directory: directory, does not exist" and exit the script
Argument 2: Should be a file (needs validated). If this does not exist, print "File: filename, does not exist" and exit the script.
If all arguments are valid, print "Given valid: filename and directory"
This is what I have so far
echo "James DuBois: 555555 - Task 1"
TIME=$(date "+%H")
if [ $TIME -lt 12 ]; then
echo "morning"
else
echo "not morning"
fi
echo "Task 2"
[ -d "$1" ] || exit
[ -d "$2" ] || exit
[ $# == 2 ] || exit
echo "arg1: $1"
echo "arg2: $2"

Answer 1

James, BASH is a wonderful, flexible shell. It has its warts, but if you need to do anything having to do with Linux system administration, etc.., you can do it in bash. Your tasks are to familiarize you with using conditional expressions (tests). There are tests for just about anything you need. That's why I pointed you to the CONDITIONAL EXPRESSIONS part of man bash.
Your second task requires the input of a filename so you can test it. I presume it is intended to be passed as an argument to your script (called positional parameters). Here is one way to approach the test. Note: I have interchanged output routines echo and printf intentionally for your benefit (printf being a bit more robust). Take a look at the following and let me know what questions you have:
#!/bin/bash
# My first script
#
# echo & printf are used at random below -- intentionally
#
[ -z $1 ] && { # validate at least 1 argument given on command line
printf "error: insufficient input. usage: %s filename\n" "${0##*/}"
exit 1
}
printf "\nJames DuBois: 5555555\n\n Task 1\n\n"
TIME=$(date "+%H")
## test for time of date: morning/not morning
if [ $TIME -lt 12 ]; then
printf " morning - time for coffee\n"
else
echo " not morning - time for scotch"
fi
echo -e "\n Task 2\n"
printf "Testing whether '%s' is a valid file.\n\n" "$1"
## test for file using compound commands
[ -f "$1" ] && echo -e " file found: '$1'\n" || printf " file not found: '%s'\n\n" "$1"
echo -e "Second test whether '$1' is a valid file.\n"
## test for file using if; then; else; fi
if [ -f "$1" ]; then
printf " file found: '%s'\n\n" "$1"
else
echo -e " file not found: '$1'\n"
fi
exit 0
Use/Output
$ bash ~/scr/tmp/stack/morningfile.sh
error: insufficient input. usage: morningfile.sh filename
$ bash ~/scr/tmp/stack/morningfile.sh mtrx_simple_dyn.c
James DuBois: 5555555
Task 1
not morning - time for scotch
Task 2
Testing whether 'mtrx_simple_dyn.c' is a valid file.
file found: 'mtrx_simple_dyn.c'
Second test whether 'mtrx_simple_dyn.c' is a valid file.
file found: 'mtrx_simple_dyn.c'
$ bash ~/scr/tmp/stack/morningfile.sh dog.c
James DuBois: 5555555
Task 1
not morning - time for scotch
Task 2
Testing whether 'dog.c' is a valid file.
file not found: 'dog.c'
Second test whether 'dog.c' is a valid file.
file not found: 'dog.c'

Answer 2

This will have some additional advantages while doing the same thing in task 2:
echo "Task 2"
[[ -d $1 && ! -L $1 && -f $2 && ! -L $2 ]] || exit
printf "%s\n" "arg1: $1" "arg2: $2"
It checks for symbolic links with the -L option.
[[ ]] has some advantages over [ ] like dealing with white spaces without the need for quoting variables.
If you want to print messages while checking for directory and file:
[[ ! -d $1 || -L $1 ]] && echo "Directory doesn't exist" && exit
[[ ! -f $2 || -L $2 ]] && echo "File doesn't exist" && exit
printf "%s\n" "arg1: $1" "arg2: $2"