This question already has answers here:
How to use double or single brackets, parentheses, curly braces
(9 answers)
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Command not found error in Bash variable assignment
(5 answers)
Closed 5 years ago.
I am trying to get the array in the while-loop and need to update the value in array too.
Below is my code what I have tried. I get this error [0: command not found
#!/bin/bash
i=0
while [$i -le "{#myarray[#]}" ]
do
echo "Welcome $i times"
i= $(($i+1)))
done
How do I fix this?
Need a space after [ and no space before or after = in the assignment. $(($i+1))) would try to execute the output of the ((...)) expression and I am sure that's not what you want. Also, you are missing a $ before the array name.
With these things corrected, your while loop would be:
#!/bin/bash
i=0
while [ "$i" -le "${#myarray[#]}" ]
do
echo "Welcome $i times"
i=$((i + 1))
done
i=$((i + 1)) can also be written as ((i++))
it is always better to enclose variables in double quotes inside [ ... ]
check your script through shellcheck - you can catch most basic issues there
See also:
Why should there be a space after '[' and before ']' in Bash?
How to use double or single brackets, parentheses, curly braces
Command not found error in Bash variable assignment
Using [ ] vs [[ ]] in a Bash if statement
Related
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Difference between single and double square brackets in Bash
(7 answers)
How can I escape a double quote inside double quotes?
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Closed 6 months ago.
I have a problem with bash, I'm trying to detect strings in a file with bash with the file looking like
cnlog "Hello World!"
When i try the [ $variable = *" ] in bash it doesn't work and throws out an error
basilc.sh: line 13: unexpected EOF while looking for matching `"'
basilc.sh: line 16: syntax error: unexpected end of file
the code of the bash file is
char=""
while IFS='' read -n1 c; do
if [ $char = '"' ] || [ $char = *" ]
then
echo "STRING FOUND"
char=""
pwd
fi
echo "$char"
done < $1
Please help
This question already has answers here:
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Difference between single and double square brackets in Bash
(7 answers)
Why is "[[ 10 < 2 ]]" true when comparing numbers in bash? [duplicate]
(1 answer)
Closed 6 months ago.
I am trying some simple input validation in bash. Basically this part of my script outputs "press [index] to select [array element]." However I cannot seem to get it to stop and exit gracefully when an invalid input is entered. From my research so far this SHOULD work:
declare -a scenarios=()
scenarios+=("Scenario_123")
scenarios+=("Scenario_456")
scenarios+=("Scenario_789")
for i in ${!scenarios[#]}; do
echo -e "select $i for ${scenarios[$i]}"
done
read ScenInd
echo ${#scenarios[#]} #[${ScenInd}=~^[0-9]+$, =~ ^[[:digit:]]+
if ! [${ScenInd}=~ ^[[:digit:]]+$ ] || [${ScenInd} < 0] || [${ScenInd} >= ${#scenarios[#]}];
then
echo "INVALID SELECTION"
exit
fi
but when I run it and enter 8, I get '[8=~: command not found'
What have I done wrong and how do I fix this? I have tried this both with [${ScenInd}=~^[0-9]+$ and =~ ^[[:digit:]]+ yet the results are the same.
Thanks in advance
This question already has answers here:
When to wrap quotes around a shell variable?
(5 answers)
Closed 1 year ago.
I just do a simple task,input a bc then if c is "+" it will print total of a+b
So i do this
echo "$a $b $c = "
if [ $c = "+" ]; then
echo $(($a + $b))
fi
And it return simple.sh: 3: [: =: unexpected operator
What is going on?? Please help, thank a lot, im so confuse now
If $c is unset or set to nothing then the expression would expand to: [ = + ] which would cause this problem.
Always quote your parameter expansions as the result will be unexpected otherwise:
[ "$c" = "+" ]
Unquoted parameter expansions will undergo word splitting and pathname expansion.
Whenever writing shellscripts it always a good idea to use the shellcheck linter, an online version is available at https://www.shellcheck.net/
This question already has answers here:
How do I compare two string variables in an 'if' statement in Bash? [duplicate]
(12 answers)
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Closed 6 years ago.
#!/bin/bash
a=0
while ["$a" -lt 10]
do
a=`expr "$a" + 1`
echo $a
done
This is the error:
a.sh: 3: a.sh: [0: not found
you need to keep spaces around your brackets:
while [ "$a" -lt 10 ]
since bash interpretes strings; it uses spaces to separate words. When you write ["$a"; then bash reads: [0 (after $a is replaced with 0)
This question already has answers here:
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Closed 6 years ago.
I am having trouble with executing the following bash script:
#!/bin/bash
response=" "
while ["$response" != "q"]; do
echo -n "Please enter a response"; read response
done
ALSO
!/bin/bash
response="x"
if ["$response" = "x"]
then
echo "the value is x"
fi
What could the possible errors be?
Your while and if statements are spaced wrong.
while [ "$response" != "q" ]; do etc
You need a space between the bracket and the double quote.