Dude, so sorry about the absolute noob question.
What is the problem with the following code?
I like to have a simple script which says MEH! when there is no input arg, otherwise prints it.
#!/bin/bash
if [${#$1}==0] then
echo "MEH!";
else
echo $1;
fi
OS says the line 4 has a error (unexpected token else at line 4).
So sorry dude.
Thanks in advance.
You probably wanted to use:
#!/bin/bash
if [ ${#1} -eq 0 ]; then
echo "MEH!";
else
echo $1
fi
Problems in your current if [${#$1}==0] then condition:
[ and ] are needed. For further information, you can check the excellent answer by Charles Bailey in Why equal to operator does not work if its not surrounded by space?.== is used on string comparison. In this case you want integer comparison, that is -eq. See Bash Conditional Expressions in the manual for a full list of them.In general, if you want to check if your script is receiving at least a parameter, you'd better do:
if [ $# -ge 1 ]; then
echo "$# parameters given"
else
echo "no parameters given"
fi
or also, as commented by Charles Duffy:
if [ -z "$1" ] # true if the variable $1 has length 0
Last and not least: check the comments below, as good information was provided.
[ ] as opposed to [[ ]], == isn't valid string comparison either; it's just that many shells support it as an extension. Better to use =, though.[ ${#1} -eq 0 ] is better written as [ -z "$1" ].
[ ${#1} -eq 0 ] occurs when the shell is invoked without any arguments. In that case the positional parameter 1 is not defined. While the length of an undefined variable defaults to 0, this isn't the recommended way to test -- it is a hack.
if [${#$1}==0] thenuseif [ $# -eq 0 ]; thenbashman page. It is quite clear about where whitespace is required and where it is forbidden.