echo "Enter a grade"
read grade
if test $grade="A"
then
basic=6000
elif test $grade="B"
then
basic=5000
else
basic=4000
fi
echo "Your basic is $basic"
When I execute this code in terminal with any grade it always returns "Your basic is 6000". what is the mistake in this code?
You need to put a space around the =.
As it is now, you just give the test command one argument, which is $grade="A", since space separates arguments. If you put spaces around =, then test will have 3 arguments, i.e. (an expanded) $grade, = and "A".
Thus:
echo "Enter a grade"
read grade
if test $grade = "A"
then
basic=6000
elif test $grade = "B"
then
basic=5000
else
basic=4000
fi
echo "Your basic is $basic"
#!/bin/bash
echo "Enter a grade"
# Read single char
read -n 1 grade
echo $grade
if [ "$grade" == 'A' ]; then
basic=6000
elif [ "$grade" == 'B' ]; then
basic=5000
else
basic=4000
fi
echo "Your basic is $basic"
Related
I would like to write a simple bash script for training multiple choice tests. Ask one question; give four choices (a, b, c, d); if user enters input, show if it is wrong or right and continue with the next question.
Here is my code so far:
#!/usr/bin/bash
echo Question1="How much is 2+2?"
echo a="1"
echo b="2"
echo c="3"
echo d="4"
read Question1
if [ "$Question1" = "d" ];
then
echo "this is correct"
else
echo "this is NOT correct"
fi
All samples about the read command example I found so far on youtube etc. stop after one question. How can I ask multiple questions? Entering another question does not work and bash shows a syntax error:
#!/usr/bin/bash
echo Question1="How much is 2+2?"
echo a="1"
echo b="2"
echo c="3"
echo d="4"
read Question1
if [ "$Question1" = "d" ];
then
echo "this is correct"
else
echo "this is NOT correct"
echo Question2="How much is 2+1?"
echo a="1"
echo b="2"
echo c="3"
echo d="4"
read Question2
if [ "$Question2" = "c" ];
then
echo "this is correct"
else
echo "this is NOT correct"
fi
It is giving you a syntax error because you don't have a fi after your first if statement, probably an error during copy/pasting.
Afterwards it should work fine.
This is where the select command is handy
PS3="How much is 2+2? "
select choice in 1 2 3 4; do
if [[ $choice == 4 ]]; then
echo "Correct"
break
fi
echo "Incorrect"
done
PS3="How much is 2+1? "
select choice in 1 2 3 4; do
if [[ $choice == 3 ]]; then
echo "Correct"
break
fi
echo "Incorrect"
done
Or, we can encapsulate the repetition in a function:
question() {
local PS3="$1 " answer=$2 choice
shift 2
select choice in "$#"; do
if [[ $choice == "$answer" ]]; then
echo "Correct"
break
fi
echo "Incorrect"
done
}
question "How much is 2+2?" 4 1 2 3 4
question "How much is 2+1?" 3 1 2 3 4
I'm trying to implement a prev option in my bash script to go back to the previous "menu", as well as a way for the script to ask for user input again if no variable is set for $name.
Heres my bash script:
#!/bin/bash
#Menu() {
for (( ; ; ))
do
beginORload=
echo "Choose option:"
echo "1 - Begin"
echo "2 - Load"
read -p "?" beginORload
#}
#Begin() {
if [ "$beginORload" -eq "1" ]
then
clear
for (( ; ; ))
do
echo "Beginning. What is your name?"
read -p "?" name
#If "prev" specified, go back to #Menu()
if [ "$name" -eq "prev" ]
then
Menu
fi
#If nothing specified, return to name input
if [ -z ${name+x} ]
then
Begin
else
break
fi
echo "Hi $name !"
done
fi
done
In batch, I could simply do:
:menu
echo Choose option:
echo 1 - Begin
echo 2 - Load
[...]
:begin
[...]
if "%name%==prev" goto menu
if "%name%==" goto begin
the issue is I keep running into errors all over the place, and I can't figure out what to type to get it to work
im running Yosemite btw. Thankyou
Something like this is close to what you expect:
while [[ $answer -ne '3' ]];do
echo "Choose option:"
echo "1 - Begin"
echo "2 - Load"
echo "3 - Exit"
read -p "Enter Answer [1-2-3]:" answer
case "$answer" in
1) while [[ "$nm" == '' ]];do read -p "What is your Name:" nm;done # Keep asking for a name if the name is empty == ''
if [[ $nm == "prev" ]];then nm=""; else echo "Hello $nm" && break; fi # break command breaks the while wrapper loop
;;
2) echo 'Load' ;;
3) echo 'exiting...' ;; # Number 3 causes while to quit.
*) echo "invalid selection - try again";; # Selection out of 1-2-3 , menu reloaded
esac # case closing
done # while closing
echo "Bye Bye!"
As a general idea you can wrap up your case selection in a while loop which will break under certain circumstances (i.e If Option 3 is selected or if a valid name is given (not blank - not prev)
PS1: In bash you compare integers with -eq , -ne, etc but you compare strings with == or !=
PS2: Check the above code online here
I m doing a simple calculator with option of choosing to continue or not . But when I try multiplying operation I get error in the console :
calculator.sh: line 17: [: too many arguments
calculator.sh: line 22: [: too many arguments
calculator.sh: line 27: [: too many arguments
calculator.sh: line 32: [: too many arguments
Which basically means all my operations has this error , but that is not true when I use them , they act normally .
I searched in stack overflow for similarities , but the examples are different . I escaped the * with slash , but I think it shouts the error in the comparing with the character "*" in order getting to the body of the if statement.
Here is the code:
#!/bin/bash
choice="Y"
while [ $choice == "Y" ]
do
echo -n "Enter first value:"
read firstvar
echo -n "Enter second value:"
read secondvar
echo -n "Enter last value:"
read compvar
echo -n "Enter operation:"
read ops
counter=0
result=0
while [ $result != $compvar ]
do
if [ $ops == "+" ]
then result=$((firstvar+secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ $ops == "-" ]
then result=$((firstvar-secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ $ops == "*" ]
then result=$((firstvar\*secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ $ops == "/" ]
then result=$((firstvar/secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
else
echo "Input valid operation !!!"
echo "Do you want to continue ? Y/N"
read choice
break
fi
counter=$((counter+1))
done
done
The problem is likely not because the "*" in script, but because of an asterisk in your $ops variable.
You should double-quote the variables to avoid globbing being applied to them; rewrite your tests like this:
elif [ "$ops" = "*" ]
Here's a very helpful resource for checking your shell scripts.
First, see the comment by Charles Duffy WRT "==" vs "=" for string tests.
Change occurrences of $ops to "${ops}".
Remove the escape in result=$((firstvar*secondvar)).
I took the liberty to reformat the script just a bit.
Hope this helps.
#!/bin/bash
choice="Y"
while [ $choice = "Y" ]
do
echo -n "Enter first value:"
read firstvar
echo -n "Enter second value:"
read secondvar
echo -n "Enter last value:"
read compvar
echo -n "Enter operation:"
read ops
counter=0
result=0
while [ $result != $compvar ]
do
if [ "${ops}" = "+" ]; then
result=$((firstvar+secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ "${ops}" = "-" ]; then
result=$((firstvar-secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ "${ops}" = "*" ]; then
result=$((firstvar*secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
elif [ "${ops}" = "/" ]; then
result=$((firstvar/secondvar))
echo "Do you want to continue ? Y/N"
read choice
break
else
echo "Input valid operation !!!"
echo "Do you want to continue ? Y/N"
read choice
break
fi
counter=$((counter+1))
done
done
Hello I don't know if this will be a duplicate , but I really don't see the error in this piece of code . It gives me an error at the then statement and I think there is no error .
I have putted comments on the two lines where the code breaks .
Here is the code:
#!/bin/bash
echo -n "Enter first value:"
read firstvar
echo -n "Enter second value:"
read secondvar
echo -n "Enter last value:"
read compvar
echo -n "Enter operation:"
read ops
counter=0
result=0
while [ $result -eq $compvar ]
do
if [ $ops -eq "+" ]
then result = $((firstvar+secondvar))
elif [ $ops -eq "-" ]
then result = $((firstvar-secondvar))
#elif[ $ops -eq "*" ]
#then result = $((firstvar\*secondvar))
#elif[ $ops -eq "/" ]
#then result = $((firstvar/secondvar))
else
echo "Input valid operation !!!"
fi
(($counter++))
done
Oh shoot , I m retarded . Missed the space between "elif" and the "[" .
You need to learn how to space and indent to have your code legible.
#!/bin/bash
echo -n "Enter first value:"; read firstvar
echo -n "Enter second value:"; read secondvar
echo -n "Enter last value:"; read compvar
echo -n "Enter operation:"; read ops
counter=0; result=0 #initialize variables
while [ $result -eq $compvar ]; do
if [ $ops = "+" ]; then
result = $((firstvar+secondvar))
elif [ $ops = "-" ]; then
result=$((firstvar-secondvar))
else
echo "Input valid operation !!!"
fi
((++counter))
done
Writing code is the same as writing literature. There are forms to use to make it easy for the reader (even if it's just you 6 months later) to follow. Your code above is confusing, and will bite you on the butt later. Add comments to.
The while loop is gratuitous and will do nothing-- the -eq should at least be -ne. The counter could be initialized as an integer to avoid problems that could arise, but it's also never used.
I am trying to write a calculator script but the first if blocks the elif. What I mean is when I try to run it I press 1 but it runs as if I pressed 2. Here is my code.
echo "For Advanced mode press 1"
echo "For Help press 2"
loop=1
while [ $loop=1 ]; do
read n
if [ $n=2 ]; then
echo "To use the calculator follow the promptings."
echo "If asked, the operators are: "
echo "* for multiplication, / for division."
echo "+ for addition, - for subtraction."
echo "% for modulus, which is division remainder"
echo "== is equal to, != is not equal to."
echo "** for exponents"
n=""
elif [ $n=1 ]; then
read a
break
fi
done
echo "_______________________"
echo "What would you like to do?"
echo "Press 1 for basic arith"
echo -n "Press 2 for geometry"
read choice
loop=2
if [ $choice=1]; then
while [ $loop=2 ]; do
echo -n "Enter X Value: "
read x
echo -n "Enter Operator: "
read op
echo -n "Enter Y Value: "
read y
ans=$((x $op y))
echo "$x $op $y = $ans"
echo "____________________"
echo "To input a new function, press enter"
read cont
done
fi
The [ built-in is used for evaluating conditions. There must be a space after the opening [ and a space before before the closing ], otherwise it's incorrect syntax.
Inside a [ ... ] expression, you can use various conditional operators. One such operator is =. You must put spaces before and after an operator, otherwise it's not recognized as an operator.
For example, [ $n=2 ] where the value of n is 1, will be evaluated as [ 1=2 ]. The 1=2 is not evaluated as a condition, because there are no spaces around it. The 1=2 will be evaluated as a string "1=2". And any non empty string in Bash is truthy, so the statement [ 1=2 ] yields true, even if it doesn't "look like" it would be true.
You must write [ "$n" = 2 ] so that = is interpreted as the conditional operator, and the expression doesn't become a single string. Note that spaces are extremely important in Bash. Spaces separate the logical elements of a program, without spaces expressions are concatenated as strings.
Also notice that I added double quotes around the variable. This is to protect the expression in case the variable is empty. If for example you write [ $n = 2 ] and the variable is empty, then the expression will be evaluated as [ = 2 ], which is a malformed expression, and the script will crash with an error.
Put spaces between your condition elements like $n = 2 not $n=2.You should pass it's arguments as whitespace separated words. So your code should be as following:
echo "For Advanced mode press 1"
echo "For Help press 2"
loop=1
while [ $loop = 1 ]; do
read n
if [ $n = 2 ]; then
echo "To use the calculator follow the promptings."
echo "If asked, the operators are: "
echo "* for multiplication, / for division."
echo "+ for addition, - for subtraction."
echo "% for modulus, which is division remainder"
echo "== is equal to, != is not equal to."
echo "** for exponents"
n=""
elif [ $n = 1 ]; then
read a
break
fi
done
echo "_______________________"
echo "What would you like to do?"
echo "Press 1 for basic arith"
echo -n "Press 2 for geometry"
read choice
loop=2
if [ $choice = 1 ]; then
while [ $loop = 2 ]; do
echo -n "Enter X Value: "
read x
echo -n "Enter Operator: "
read op
echo -n "Enter Y Value: "
read y
ans=$((x $op y))
echo "$x $op $y = $ans"
echo "____________________"
echo "To input a new function, press enter"
read cont
done
fi