I'm trying to write a script that will check two error flags, and in case one flag (or both) are changed it'll echo-- error happened. My script:
my_error_flag=0
my_error_flag_o=0
do something.....
if [[ "$my_error_flag"=="1" || "$my_error_flag_o"=="2" ] || [ "$my_error_flag"="1" && "$my_error_flag_o"="2" ]]; then
echo "$my_error_flag"
else
echo "no flag"
fi
Basically, it should be, something along:
if ((a=1 or b=2) or (a=1 and b=2))
then
display error
else
no error
fi
The error I get is:
line 26: conditional binary operator expected
line 26: syntax error near `]'
line 26: `if [[ "$my_error_flag"=="1" || "$my_error_flag_o"=="2" ] || [ "$my_error_flag"="1" && "$my_error_flag_o"="2" ]]; then'
Are my brackets messed up?
Use -a (for and) and -o (for or) operations.
tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_01.html
Update
Actually you could still use && and || with the -eq operation. So your script would be like this:
my_error_flag=1
my_error_flag_o=1
if [ $my_error_flag -eq 1 ] || [ $my_error_flag_o -eq 2 ] || ([ $my_error_flag -eq 1 ] && [ $my_error_flag_o -eq 2 ]); then
echo "$my_error_flag"
else
echo "no flag"
fi
Although in your case you can discard the last two expressions and just stick with one or operation like this:
my_error_flag=1
my_error_flag_o=1
if [ $my_error_flag -eq 1 ] || [ $my_error_flag_o -eq 2 ]; then
echo "$my_error_flag"
else
echo "no flag"
fi
You can use either [[ or (( keyword. When you use [[ keyword, you have to use string operators such as -eq, -lt. I think, (( is most preferred for arithmetic, because you can directly use operators such as ==, < and >.
Using [[ operator
a=$1
b=$2
if [[ a -eq 1 || b -eq 2 ]] || [[ a -eq 3 && b -eq 4 ]]
then
echo "Error"
else
echo "No Error"
fi
Using (( operator
a=$1
b=$2
if (( a == 1 || b == 2 )) || (( a == 3 && b == 4 ))
then
echo "Error"
else
echo "No Error"
fi
Do not use -a or -o operators Since it is not Portable.
Please try following
if ([ $dateR -ge 234 ] && [ $dateR -lt 238 ]) || ([ $dateR -ge 834 ] && [ $dateR -lt 838 ]) || ([ $dateR -ge 1434 ] && [ $dateR -lt 1438 ]) || ([ $dateR -ge 2034 ] && [ $dateR -lt 2038 ]) ;
then
echo "WORKING"
else
echo "Out of range!"
You can get some inspiration by reading an entrypoint.sh script written by the contributors from MySQL that checks whether the specified variables were set.
As the script shows, you can pipe them with -a, e.g.:
if [ -z "$MYSQL_ROOT_PASSWORD" -a -z "$MYSQL_ALLOW_EMPTY_PASSWORD" -a -z "$MYSQL_RANDOM_ROOT_PASSWORD" ]; then
...
fi
Related
This question already has answers here:
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Closed 3 years ago.
I'm trying to do test automation with a bash script using if then else statements but I'm running into a few errors. For one, when I try to execute it I'm doing something wrong with the variable assignment with j and k, because it tells me that the command j and the command k aren't found when I try to execute. How do you correctly create variables?
The most confusing thing though is when I try to execute the script I get an error telling me I have an unexpected token near fi, and then it just says 'fi'. What am I doing wrong here?
#!/bin/bash
j = 0
k = 0
echo Test1:
echo -ne "0\nIn\nUG\n" | /u/cgi_web/Tuition/cost
echo Test2:
echo -ne "0\nOut\nUG\n" | /u/cgi_web/Tuition/cost
echo Test3:
echo -ne "0\nIn\nGR\n" | /u/cgi_web/Tuition/cost
echo Test4:
echo -ne "0\nOut\nGR\n" | /u/cgi_web/Tuition/cost
for i in {1..17}
do
echo Test$((i+4)):
if[ "$j" -eq 0 ] && [ "$k" -eq 0 ] then
$j = 1
echo -ne "$i\nIn\nUG\n" | /u/cgi_web/Tuition/cost
elif[ "$j" -eq 1 ] && [ "$k" -eq 0 ] then
$k = 1
echo -ne "$i\nIn\nGR\n" | /u/cgi_web/Tuition/cost
elif[ "$j" -eq 1 ] && [ "$k" -eq 1 ] then
$j = 0
echo -ne "$i\nOut\nUG\n" | /u/cgi_web/Tuition/cost
elif[ "$j" -eq 0 ] && [ "$k" -eq 1 ] then
$k = 0
echo -ne "$i\nOut\nGR\n" | /u/cgi_web/Tuition/cost
fi
done
EDIT: I figure out the variable issue with j and k, I had to remove the spaces in the statement.
Bash if statements require a semi-colon before the then:
if [ condition ] || [ condition ]; then
# code
elif [ condition ] && [ condition ]; then
# code
fi
For example.
To help anyone who might look at this for help in the future, I figured I'd answer my own question with all the syntax errors I found from my own testing and with the helpful responses of others.
To start the variable assignment:
j = 0
you can't have spaces in between, so it would be:
j=0
Also if statements need a space between if and the bracket and need a semicolon after the last bracket before then. Therefore my incorrect if statement
if[ "$j" -eq 0 ] && [ "$k" -eq 0 ] then
becomes
if [ "$j" -eq 0 ] && [ "$k" -eq 0 ]; then
or instead of a semicolon you can have a new line between the bracket, so it would become
if [ "$j" -eq 0 ] && [ "$k" -eq 0 ]
then
Actually I am a new bash learner. I can use one condition in bash command. But how to use multiple condition in bash? I can use if statement like this:
read a
if [ $a = "y" ] ; then
echo "YES"
elif [ $a = "Y" ] ; then
echo "YES"
else
echo "NO"
fi
I am finding something like this:
read a b c
if [ $a -eq $b and $b -eq $c ] ; then
echo "EQUILATERAL"
elif [ $a -eq $b or $b -eq $c ] ; then
echo "ISOSCELES"
else
echo "SCALENE"
fi
I just want to know, what to use instead of and and or?
Use && for and (|| for or)
read a b c
if [ "$a" == "$b" ] && [ "$b" == "$c" ] ; then
echo "EQUILATERAL"
elif [ "$a" == "$b" ] || [ "$b" == "$c" ] ; then
echo "ISOSCELES"
else
echo "SCALENE"
fi
Use && and || to have multiple conditions. Additionally, change the square brackets to parentheses. Additionally change the -eq to == since you're comparing numbers and not strings. This works:
#!/bin/bash
read a b c
if (( $a == $b )) && (( $b == $c )); then
echo "EQUILATERAL"
elif (( $a == $b )) || (( $b == $c )) ; then
echo "ISOSCELES"
else
echo "SCALENE"
fi
In addition to the prior answers, the correct way to use compound expression in a single [ or test (they are the same) clause is to use -a (for and) and -o (for or).
(e.g. testing if both file1 and file2 are readable):
if [ -r "$file1" -a -r "$file2 ]
then
# do something with the files
fi
Using test itself:
if test -r "$file1" -a -r "$file2
then
# do something with the files
fi
The portable way of doing this inside test brackets is to use -a and -o. Beware however that -eq is a numeric comparison, so you need to make sure your variables are numeric before comparing them. Something like this:
#! /bin/sh
read a b c
expr "$a" : '[0-9][0-9]*$' \& "$b" : '[0-9][0-9]*$' \& "$c" : '[0-9][0-9]*$' >/dev/null || exit
if [ $a -eq $b -a $b -eq $c ] ; then
echo "EQUILATERAL"
elif [ $a -eq $b -o $b -eq $c ] ; then
echo "ISOSCELES"
else
echo "SCALENE"
fi
I'm learning BASH through HackerRank.There's an exercise in which the lengths of the triangle is given and then you need to find whether the triangle is isosceles,scalene or equilateral.I wrote the following code:
read a
read b
read c
if [ [ "$a" -eq "$b" ] && [ "$b" -eq "$c" ] ]
then
echo "EQUILATERAL"
elif [ [ "$a" -eq "$b" ] || [ "$b" -eq "$c" ] ]
then
echo "ISOSCELES"
else
echo "SCALENE"
fi
But then I get the following error
solution.sh: line 4: [: too many arguments
solution.sh: line 7: [: too many arguments
solution.sh: line 7: [: too many arguments
Why is this happening? I tried long and hard to rectify it but nothing worked out
You can combine conditions either ommiting the surrounding brackets like this
if [ "$a" -eq "$b" ] && [ "$b" -eq "$c" ]
or by combining the conditions with -a/-o like this
if [ "$a" -eq "$b" -a "$b" -eq "$c" ]
see http://wiki.bash-hackers.org/commands/classictest#and_and_or
&& and || are Bash list operators. In a chain of commands, the next command is executed only if the previous command returned 0 (&&) or nonzero (||).
[ is an alias for the Bash internal test command and has arguments such as -eq or -ne. ] ends its command line. Type help test for more information.
So if you write a conditional expression, you do not put the list operators inside brackets.
Try, for example, this instead of the respective line in your code:
if [ "$a" -eq "$b" ] && [ "$b" -eq "$c" ]
then
[ isn't a grouping operator in bash, you can't use it to group tests.
there are a number of different ways to express the tests you want to make, numeric evaluation mode is probably easiest to read
if (( a == b && b == c ))
if (( a == b || b == c || c == a ))
This is going to break if you have decimal fractions, but will work fine for integers.
[ is a conditional command, like an alias for sh's test built-in command.
[[ is the same for bash which has more test options.
So make a choice between [ and [[ but not [ [ which means two command.
Example:
# [ [ -n 'test' ] ]
bash: [: too many arguments
# [ -n 'test' ] && echo $?
0
# [[ -n 'test' ]] && echo $?
0
When I run this bash script :
if [ [$EUID -ne 0] ]; then
echo "This script must be run as root" 1>&2
exit 1
else
printf " whathever "
exit 0
fi
I have this error :
./myScript: 15: [: Illegal number: [
Do you see any problem ?
You have syntax error in your if condition, use this if condition:
if [ "$EUID" -ne 0 ];
OR using [[ and ]]
if [[ "$EUID" -ne 0 ]];
You have syntax error in your if condition, use this if condition:
if [ "$EUID" -ne 0 ];
OR using [[ and ]]
if [[ "$EUID" -ne 0 ]];
If you use the KSH88+/Bash 3+ internal instruction [[, it's not necessary to use doubles quotes around the variables operands :
[ ~/test]$ [[ $var2 = "string with spaces" ]] && echo "OK" || echo "KO"
OK
Instead of the external command test or his fork [ :
[ ~/test]$ [ $var2 = "string with spaces" ] && echo "OK" || echo "KO"
bash: [: too many arguments
KO
[ ~/test]$ [ "$var2" = "string with spaces" ] && echo "OK" || echo "KO"
OK
Of course, you also have to choose the operators according to the type of operands :
[ ~/test]$ var1="01"
[ ~/test]$ [ "$var1" = "1" ] && echo "OK" || echo "KO"
KO
[ ~/test]$ [ "$var1" -eq "1" ] && echo "OK" || echo "KO"
OK
two suggestions apart from what everyone else has pointed out already.
rather than doing else [bunch of code because we are root] fi, just replace the else with fi. once you've tested for the failure condition you are concerned about and taken appropriate action, no need to continue to be within the body of the conditional.
$EUID is a bashism, if you would like to make this portable to shells such as ksh, replacing it with:
if [ $(id -u) -ne 0 ]; then echo "ur not root bro"; exit 1; fi
would be a good way to do it.
using
sudo bash shell_script.sh
instead of
sudo sh shell_script.sh
solved in my case.
I was modifying an script didn't know how to write more than one condition in an if statement. I want to connect the two condition with an AND.
if [ envoi1 -eq 2 ];then
if [ envoi2 -eq 0 ];then
echo 'Ahora mismo.'
envoi = 1
fi
else
if [ envoi2 -eq 1 ];then
if [ envoi1 -eq 1 ];then
echo 'Situacion Normal.'
envoi = 1
fi
else
echo 'Raruno'
envoi=`expr $envoi1 + envoi2`
fi
fi
Now i use nested if to do the same but the code it's not so clear for me.
try this:
if [ $envoi1 -eq 2 ] && [ $envoi2 -eq 0 ] ; then
envoi = 1
fi
In bash, you can use [[ as follows:
if [[ $envoi2 -eq 1 && $envoi1 -eq 1 ]]; then
echo "Situacion Normal."
envoi=1
fi
However, [[ is not POSIX and will not work if you are using the /bin/sh shell. So if portability is desired use:
if [ $envoi2 -eq 1 -a $envoi1 -eq 1 ]; then
echo "Situacion Normal."
envoi=1
fi
Also note that when assigning variables you should not have any spaces on either side of the =.