4.6 Examining Source Files (‘list’)

the BASH debugger can print parts of your script’s source. When your script stops, the BASH debugger spontaneously prints the line where it stopped. Likewise, when you select a stack frame (see Selecting a frame), the BASH debugger prints the line where execution in that frame has stopped. You can print other portions of source files by explicit command.

If you use the BASH debugger through its GNU Emacs interface, you may prefer to use Emacs facilities to view source.

To print lines from a source file, use the list command (abbreviated l). By default, ten lines are printed. There are several ways to specify what part of the file you want to print.

Here are the forms of the list command most commonly used:

list linenum

l linenum

Print lines centered around line number linenum in the current source file.

list function

l function

Print the text of function.

list

l

Print more lines. If the last lines printed were printed with a list command, this prints lines following the last lines printed; however, if the last line printed was a solitary line printed as part of displaying a stack frame (see Examining the Stack), this prints lines centered around that line.

list -

l -

Print lines just before the lines last printed.

By default, the BASH debugger prints ten source lines with any of these forms of the list command. You can change this using set listsize:

set listsize count

Make the list command display count source lines (unless the list argument explicitly specifies some other number).

show listsize

Display the number of lines that list prints.

Repeating a list command with RET discards the argument, so it is equivalent to typing just list. This is more useful than listing the same lines again. An exception is made for an argument of ‘-’; that argument is preserved in repetition so that each repetition moves up in the source file.

In general, the list command expects you to supply a linespecs. Linespecs specify source lines; there are several ways of writing them, but the effect is always to specify some source line.

Here is a complete description of the possible arguments for list:

list linespec

Print lines centered around the line specified by linespec.

list first increment

Print increment lines starting from first

list first

Print lines starting with first.

list -

Print lines just before the lines last printed.

list .

Print lines after where the script is stopped.

list

As described in the preceding table.

Here are the ways of specifying a single source line—all the kinds of linespec.

number

Specifies line number of the current source file. When a list command has two linespecs, this refers to the same source file as the first linespec.

filename:number

Specifies line number in the source file filename.

function

Specifies the line that function function is listed on.