#### 1.22.1 Substitution of system commands in backquotes

Command-line substitution is specified by a system command enclosed in backquotes. This command is spawned and the output it produces replaces the backquoted text on the command line. Some implementations also support pipes; see special-filenames.

Command-line substitution can be used anywhere on the ‘gnuplot‘ command line, except inside strings delimited by single quotes.

Example:

This will run the program ‘leastsq‘ and replace ‘leastsq‘ (including backquotes) on the command line with its output:

          f(x) = `leastsq`

or, in VMS

          f(x) = `run leastsq`

These will generate labels with the current time and userid:

          set label "generated on `date +%Y-%m-%d` by `whoami`" at 1,1
          set timestamp "generated on %Y-%m-%d by `whoami`"