bash shell script syntax error [duplicate]
-
10-07-2019 - |
Question
This question already has an answer here:
I wrote a function in bash script. However, it's complaining about syntax. I really can't see what is it..... the error message is [: missing `]'
addem() {
if [ $# -eq 0] || [ $# -gt 2 ]
then
echo -1
elif [ $# -eq 1 ]
then
echo $[ $1 + $1 ]
else
echo $[ $1 + $2 ]
fi
}
Solution
You need a space before the first ]
. That is:
change:
if [ $# -eq 0] || [ $# -gt 2 ]
to:
if [ $# -eq 0 ] || [ $# -gt 2 ]
OTHER TIPS
Try:
if [ $# -eq 0 ] || [ $# -gt 2 ]
(There was no space between 0 and ].)
indyK1ng: The "#" is not treated as a comment, since the "$" escapes the next character. The "$#" is an internal variable representing the number of positional parameters that exist at the current context. This can be thought of as the number of command line arguments to the shell script, but that array can be reset using the "set -- [args]" built in.
Joakim Elofsson: The overall structure of the if statement is correct, the ";" is only required before the "then" and before the "fi" if those are not listed on a separate line.
The problem is the space between the "0" and the bracket. Bash requires that brackets used to delimit conditional expressions be set off with at least a single space from the expression.
if [ $# -eq 0] || [ $# -gt 2 ] # Wrong
if [ $# -eq 0 ] || [ $# -gt 2 ] # Correct
On an additional note, the two conditional expressions can be combined. The operator association will ensure that everything works out.
if [ $# -eq 0 -a $# -gt 2 ] # Even Better
I tend to prefer the expanded features offered with double brackets for expression evaluation. Note that the combination of the two evaluations is done with a different operator. I find this to be more readable.
if [[ $# -eq 0 || $# -gt 2 ]] # My preference
Later in the script, the use of single brackets for integer addition is not recommended. The single brackets are evaluating an expression to a boolean. Double parens are used for integer math.
echo $[ $1 + $1 ] # Evaluation of an expression
echo $(( $1 + $1 )) # Integer math
Bash is sensitive to spaces. In your first line, replace if [ Y -eq X] with [ Y -eq X ] (space before the "]")
I would use extended test constructs (BASH) as demonstrated bellow. I think it would reduce the no of characters and increase readability (at least for programmers). :-)
addem() {
if (( $# == 0 || $# > 2 ))
then
echo -1
elif (( $# == 1 ))
then
echo (( $1 + $1 ))
else
echo (( $1 + $2 ))
fi
}
You should avoid brackets and use test
instead:
if test $# -eq 0 || test $# -gt 2
then
echo -1
elif test $# -eq 1
then
echo $(( $1 + $1 ))
else
echo $(( $1 + $2 ))
fi
Getting a better shell style will make you much better. :)