Shell Programming and Scripting

Hi, I'm having trouble with a simple copy command in a script on HPUX.

I am trying to copy a file and append date & time.

The echo command prints out what I am expecting..

Code:

echo "Backing up $file to $file.$DATE.$FIXNUM" | tee -a $LOGFILE

+ echo 'Backing up /home/efin/gp/source/kerf/verlist.pc to /home/efin/gp/source/kerf/verlist.pc.20150602.12345'

However, the copy copies the filename to $DATE.FIXNUM ..

Code:

cp $file $file_$DATE.$FIXNUM | tee -a $LOGFILE
+ cp /home/efin/gp/source/kerf/verlist.pc 20150602.12345

Thanks in advance

You see the subtle difference between the two?

Well, i won't tell you the difference... but

When using shell variables clustered like that together, use ${VAR} for everything to expand properly.

For instance $FILE_$NAME_$DATE will not expand correctly unless used in such manner e.g. ${FILE}_${NAME}_${DATE}


Hope that helps
Regards
Peasant.

Oh, come on. Let's stop beating around the bush...
The shell knows that underscore (_) and period (.) are not the same thing, and you should recognize that too.

If a shell variable name is to be expanded in a string where the variable name is immediately followed by a character that can also be part of a shell variable name, the variable name must be surrounded by braces ({ and }) to keep the following character from being interpreted as part of the variable name. Valid simple shell variable names are strings of one or more alphanumeric characters and underscores where the 1st character is not numeric.

So, if three shell variables are to be expanded separated by underscores, you need braces to keep the underscores separate from the variable names. But if three shell variables are to be expanded separated by periods, the braces are not needed (but won't hurt if they are included).

Thanks for the helpful and non helpful replies

Putting the braces around the variables sorted it. doh !

Apologies for my n00bness.