The set xlabel command sets the x axis label. Similar commands set labels on the other axes.
Syntax:
set xlabel {"<label>"} {<xoff>}{,<yoff>} {"<font>{,<size>}"}
show xlabel
The same syntax applies to x2label, ylabel, y2label and zlabel.
Specifying the constants <xoff> or <yoff> as optional offsets for a label will move it <xoff> or <yoff> character widths or heights. For example, " set xlabel -1" will change only the x offset of the xlabel, moving the label roughly one character width to the left. The size of a character depends on both the font and the terminal.
<font> is used to specify the font in which the label is written; the units of the font <size> depend upon which terminal is used.
To clear a label, put no options on the command line, e.g., "set y2label".
The default positions of the axis labels are as follows:
xlabel: The x-axis label is centered below the bottom axis.
ylabel: The position of the y-axis label depends on the terminal, and can be one of the following three positions:
1. Horizontal text flushed left at the top left of the plot. Terminals that cannot rotate text will probably use this method. If set x2tics is also in use, the ylabel may overwrite the left-most x2tic label. This may be remedied by adjusting the ylabel position or the left margin.
2. Vertical text centered vertically at the left of the plot. Terminals that can rotate text will probably use this method.
3. Horizontal text centered vertically at the left of the plot. The EEPIC, LaTeX and TPIC drivers use this method. The user must insert line breaks using \\ to prevent the ylabel from overwriting the plot. To produce a vertical row of characters, add \\ between every printing character (but this is ugly).
zlabel: The z-axis label is centered along the z axis and placed in the space above the grid level.
y2label: The y2-axis label is placed to the right of the y2 axis. The position is terminal-dependent in the same manner as is the y-axis label.
x2label: The x2-axis label is placed above the top axis but below the plot title. It is also possible to create an x2-axis label by using new-line characters to make a multi-line plot title, e.g.,
set title "This is the title\n\nThis is the x2label"
Note that double quotes must be used. The same font will be used for both lines, of course.
If you are not satisfied with the default position of an axis label, use set label instead--that command gives you much more control over where text is placed.
Please see set syntax for further information about backslash processing and the difference between single- and double-quoted strings.