Curly Braces Substitution

A device called curly braces substitution is provided to enable expressions to be inserted into command lines. The expression to be evaluated is simply enclosed in curly braces {<expression>} in the command line. Such substitution can be used in any command line. For example, the name of a data file might be assigned to the symbolic name DATA and it is required to make a copy of this file for some reason. Curly braces substition can be used in the command line to achieve this.

qcl>DATA='joke.dat'
qcl>NEWFILE='another.dat'
qcl>$cp {DATA} {NEWFILE}

The command line passed to the system will be

         
cp joke.dat another.dat

In this way assigned strings can easily be included in command lines using their symbolic name or expressions involving symbolic names.