Bash help

druadunc91 · 01-25-2013, 01:56 PM

Hey there,

I'm new here and currently taking Bash Programming in college. I'm having a little problem right now with my code

i'm trying to have my program output the date/time whenever a user inputs the word "time" when my program prompts them to enter something

so far this is what the code looks like and I'm getting an integer expression expected

Quote:

clear
echo; echo; echo
echo -n Enter something: ' '
read x
if [ "$x" -eq "time"]
then
echo date
fi

what am I forgetting?

jpollard · 01-25-2013, 02:13 PM

-eq is a numeric comparison.

You want either == (or = when used in an expression), also suggest space after the closing " on "time".

Run down the bash manpage to "Conditional Expressions"

druadunc91 · 01-25-2013, 02:15 PM

that worked, thanks! I'll be back for more help soon, probably

question: with if statements, if you have an if inside an if, do you need a fi at the end of the inner if statement

example:

Quote:

if [blah blah]
then
echo `blah`
if [blah1 blah1]
then
echo `blah1`
fi
fi

YankeePride13 · 01-25-2013, 02:28 PM

Quote:

Originally Posted by druadunc91

that worked, thanks! I'll be back for more help soon, probably

question: with if statements, if you have an if inside an if, do you need a fi at the end of the inner if statement

example:

yes.

druadunc91 · 01-25-2013, 03:35 PM

Ok,

so more problems.

Here's my code:

Quote:

clear
echo;echo;echo
echo -n Enter something: ' '
read x
if [ "$x" = "time"]
then
echo `date`
elif [ "$x" = "Directory"
then
echo `pwd`
fi
else [ "$x" = "Who"]
then
echo `who`
fi

When I enter "Directory" as my input, it tells me where I am at in my assignment. So the the output for me looks like this:

Quote:

/home/druadunc/csc490/bin

but there is more. after that it shows:

Quote:

./task02: line 12: syntax error near unexpected token 'else'

so im getting the correct output, but im getting an error message for my last if that I have. the statement bolded is the one with the error message

jpollard · 01-25-2013, 03:41 PM

And the question is?

Habitual · 01-25-2013, 04:05 PM

Quote:

Here's my code:...

doesn't

Code:

elif [ "$x" = "Directory"

need a closing "]"?, so

Code:

elif [ "$x" = "Directory" ]

?

2 of the 3 braces need spaces before the closing right bracket.
time" ] and who" ] NOT
time"] or who"]

http://tldp.org/LDP/abs/html/testcon...ml#DBLBRACKETS

druadunc91 · 01-25-2013, 04:06 PM

Quote:

Originally Posted by Habitual

doesn't

Code:

elif [ "$x" = "Directory"

need a closing "]"?, so

Code:

elif [ "$x" = "Directory" ]

?

sorry, i forgot to type then in the post...i have it in my coding

druuna · 01-25-2013, 04:09 PM

Quote:

Originally Posted by druadunc91

Code:

clear
echo;echo;echo
echo -n Enter something: ' '
read x
if [ "$x" == "time" ]  # you need == and not = / missing space between " and ]
then 
echo `date`
elif [ "$x" == "Directory" ]  # == -> = / missing square bracket
then
echo `pwd`
# if             # you need to use elif instead of if  else
#else
elif [ "$x" == "Who" ]  # == -> = / also needs an extra space.
then
echo `who`
fi

And those are to make the code work.

You might want to have a look at these:

Bash resources:

druadunc91 · 01-25-2013, 04:10 PM

thanks for the help and info druuna!

on the who command, how do you get each user to appear on their own line so its not all mashed up?

suicidaleggroll · 01-25-2013, 04:27 PM

Quote:

Originally Posted by druadunc91

thanks for the help and info druuna!

on the who command, how do you get each user to appear on their own line so its not all mashed up?

You don't need to use echo for any of those commands, as that's what they'll do anyway. Just run the command, eg:

Code:

elif [ "$x" == "Who" ]
then
   who
fi

Same goes for date and pwd. You use the back ticks or $() when you want to execute something and pass the output into something else, such as a variable for parsing later on. Passing it into echo is rather pointless, as that's what the command is going to do anyway (plus echo will jumble up the line ends).

You may also want to start indenting your if blocks, it makes larger codes infinitely easier to read.

druadunc91 · 01-26-2013, 02:08 PM

added another elif statement, because my assignment seems to contain a lot of them. Anyways, all my scripts are working except for the last elif statement.

This is the error I get when I execute the script using the "trigger" work if you will.

Quote:

line 20: syntax error near unexpected token `elif'
line 20: elif [ "$x" == "Quit" ]'

Thats the error, section of code it goes to

Quote:

elif [ "$x" == "Quit' ]
then
echo Something

so, whats wrong with the script? I even tried changing echo Something to just `exit` to see if it would work, and it doesn't

druuna · 01-26-2013, 02:24 PM

Quote:

Originally Posted by druadunc91

[code]elif [ "$x" == "Quit' ]
then
echo Something

You can't mix double and single quotes. A set of either has their own behavioural purpose (in short: one does allow expanding (""), the other doesn't ('').

druadunc91 · 01-26-2013, 02:28 PM

That was my bad on typing here. My script has "". Still have same error

druuna · 01-26-2013, 02:30 PM

Please post the complete script, or at least the complete if-then-elif-fi part that doesn't work. Also post the exact error it throws.