# if [ "$1" != "Trail" -a "$1" != "Image" ]; then"
Well....maybe.
You can take some actions / set of actions if $1 is not "Trail" and is not "Image", else do something else (optional).
This is the case with the test above. Had $1 been "Junk" it would have fallen thru / hit the else clause if present.
Another possibility is: you can take some actions / set of actions if $1 is *either* "Trail" or "Image", else do something else. in that case "if [ "$1" = "Trail" -o "$1 = "Image" ] ; then" would be appropriate
Depends on the OPs intent was. Since the basic logic posted was wrong, then either could apply, although I suspect that JRF has right.
You can make other cases by negating the logic to force it thru the "then" else, instead of the "else" clauses, but I'll not muddy the waters further
"You can make other cases by negating the logic to force it thru the "then" CLAUSES, instead of the "else" clauses, but I'll not muddy the waters further
Happy to see many replies overnight. Anyway. Thanks for the replies
This works finally.. if [[ "$1" != Trail && "$1" != Image ]]
The intention was I want the parameter either Trail or Image. If it is trail do something or Image do something. I thought `and` will always check both conditions.
I tried all the above solutions but getting error. However still -a should work on strings. What is the syntax using the -a? I tried all the combinations.
>I tried all the above solutions but getting error.
What's your error?
>However still -a should work on strings.
Yes -a works on boolean conditions. If $1 isn't Trail nor Image, it echoes bad #. if [ "$1" != "Trail" -a "$1" != "Image" ]; then echo "bad 1" fi if [[ "$1" != Trail && "$1" != Image ]]; then echo "bad 2" fi [ "$1" != Trail ] && [ "$1" != Image ] && echo "bad 3"
The intention was I want the parameter either Trail or Image. If it is trail do something or Image do something. I thought `and` will always check both conditions."
uh... in that case, I'd have thought something like
if [[ "$1" = Trail -o "$1" = Image ]]
would have been more appropriate, as you seem to be stating you want $1 to be either Trail or Image.
The test you posted will NOT run anything if $1 is "Trail" or "Image" but would run if $1 were, say, "Junk"
here's Dennis' test case modified to match the stated goal of:
"The intention was I want the parameter either Trail or Image. If it is trail do something or Image do something. I thought `and` will always check both conditions."
# if $1 is Trail or Image, it echoes found #. echo $1 if [ "$1" = "Trail" -o "$1" = "Image" ]; then echo "found 1" fi if [[ "$1" = Trail || "$1" = Image ]]; then echo "found 2" fi [ "$1" = Trail ] || [ "$1" = Image ] && echo "found 3"
one of the many answers above should match what you are attempting to do. But since you state one case, then choose the logic for the other, it's really tough to tell what the heck you really want
uh... in that case, I'd have thought something like
if [[ "$1" = Trail -o "$1" = Image ]]
would have been more appropriate, as you seem to be stating you want $1 to be either Trail or Image.
The test you posted will NOT run anything if $1 is "Trail" or "Image" but would run if $1 were, say, "Junk" -------------------------------
This is where i used my condition. Did i construct the code badly ?
if [ "$1" != "Trail" -a "$1" != "Image" ]; then echo "Check the case" exit fi #Then I start with statements for the parameter while [ $1 == Trail ] do done
My confusion revolved around your statement(s) like:
"The intention was I want the parameter either Trail or Image. If it is trail do something or Image do something. I thought `and` will always check both conditions."
-AND- the illustrated "IF" test
if [ "$1" != "Trail" -a "$1" != "Image" ]; then
After seeing your code snippet, I'd have said that your intention was to check if $1 was either "Trail" or "Image", and stop if not. This became clear when you posted some addtional code.
"if [ "$1" != "Trail" -a "$1" != "Image" ]; then echo "Check the case" exit fi"
Actual code posted seems to be just fine. As Dennis noted, "case" may be a more elegant solution, or it have been written as series of if/elseif/elseif...statements.
As i stuck with If syntax i just want to know the whats issue is. As you said its always better to give more information instead of pasting it a single line code.
This will help others to give thier inputs correctly.
