gdb.info: Output

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Commands for controlled output

During the execution of a command file or a user-defined command, normal
GDB output is suppressed; the only output that appears is what is
explicitly printed by the commands in the definition.  This section
describes three commands useful for generating exactly the output you
want.
`echo TEXT'
     Print TEXT.  Nonprinting characters can be included in TEXT using
     C escape sequences, such as `\n' to print a newline.  *No newline
     is printed unless you specify one.* In addition to the standard C
     escape sequences, a backslash followed by a space stands for a
     space.  This is useful for displaying a string with spaces at the
     beginning or the end, since leading and trailing spaces are
     otherwise trimmed from all arguments.  To print ` and foo = ', use
     the command `echo \ and foo = \ '.
     A backslash at the end of TEXT can be used, as in C, to continue
     the command onto subsequent lines.  For example,
          echo This is some text\n\
          which is continued\n\
          onto several lines.\n
     produces the same output as
          echo This is some text\n
          echo which is continued\n
          echo onto several lines.\n
`output EXPRESSION'
     Print the value of EXPRESSION and nothing but that value: no
     newlines, no `$NN = '.  The value is not entered in the value
     history either.  *Note Expressions: Expressions, for more
     information on expressions.
`output/FMT EXPRESSION'
     Print the value of EXPRESSION in format FMT.  You can use the same
     formats as for `print'.  *Note Output formats: Output Formats, for
     more information.
`printf STRING, EXPRESSIONS...'
     Print the values of the EXPRESSIONS under the control of STRING.
     The EXPRESSIONS are separated by commas and may be either numbers
     or pointers.  Their values are printed as specified by STRING,
     exactly as if your program were to execute the C subroutine
          printf (STRING, EXPRESSIONS...);
     For example, you can print two values in hex like this:
          printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
     The only backslash-escape sequences that you can use in the format
     string are the simple ones that consist of backslash followed by a
     letter.