Single [] are posix shell compliant condition tests. Double [[]] are an extension to the standard [] and are supported by bash and other shells (e.g. zsh, ksh). They support extra operations (as well as the standard posix operations). For example: || instead of -o and regex matching with =~. A fuller list of differences … Read more
You can run your command without any additional syntax. For example, the following checks the exit code of grep to determine whether the regular expression matches or not: if ! grep -q “$word” /usr/share/dict/words then echo “Word $word is not valid word!” fi
You can use && for logical and || for logical or so you can do if a > 0 && i == j || f < 3 { … } see here https://developer.apple.com/library/ios/documentation/swift/conceptual/Swift_Programming_Language/BasicOperators.html
I might be a little bit late, but you could give this a try inside your function: if (‘itemName’ in item) { name = item.itemName; } else { name = item.itemTitle; }
if echo “$long_str” | grep -q “$shrt_str”;then echo “found” fi or echo “$long_str” | grep -q “$shrt_str” && echo “found” || echo “not found” But since you are using bash shell, then use shell internals. No need to call external commands shrt_str=”guide” case “$long_str” in *”$shrt_str”* ) echo “Found”;; * ) echo “Not found”;; esac
Your problem stems from a misunderstanding of the or operator that is common to people learning programming languages like this. Yes, your immediate problem can be solved by writing x ~= 0 and x ~= 1, but I’ll go into a little more detail about why your attempted solution doesn’t work. When you read x … Read more
Yes! Here you have another example: UPDATE prices SET final_price= CASE WHEN currency=1 THEN 0.81*final_price ELSE final_price END This works because MySQL doesn’t update the row, if there is no change, as mentioned in docs: If you set a column to the value it currently has, MySQL notices this and does not update it.
The generated byte code is identical for those two cases, so it’s purely a matter of style. I produced two methods e1 and e2 and both produced this byte code (read using javap -v): public boolean e1(java.lang.Object); Code: Stack=2, Locals=2, Args_size=2 0: aload_0 1: aload_1 2: if_acmpne 7 5: iconst_1 6: ireturn 7: aload_1 8: … Read more
You forgot braces around the if block, and a semicolon between the statements in the block. awk ‘{if($3 != 0) {a = ($3/$4); print $0, a;} else if($3==0) print $0, “-” }’ file > out