gdb: Input/Output
4.6 Your Program's Input and Output
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By default, the program you run under GDB does input and output to the
same terminal that GDB uses. GDB switches the terminal to its own
terminal modes to interact with you, but it records the terminal modes
your program was using and switches back to them when you continue
running your program.
'info terminal'
Displays information recorded by GDB about the terminal modes your
program is using.
You can redirect your program's input and/or output using shell
redirection with the 'run' command. For example,
run > outfile
starts your program, diverting its output to the file 'outfile'.
Another way to specify where your program should do input and output
is with the 'tty' command. This command accepts a file name as
argument, and causes this file to be the default for future 'run'
commands. It also resets the controlling terminal for the child
process, for future 'run' commands. For example,
tty /dev/ttyb
directs that processes started with subsequent 'run' commands default to
do input and output on the terminal '/dev/ttyb' and have that as their
controlling terminal.
An explicit redirection in 'run' overrides the 'tty' command's effect
on the input/output device, but not its effect on the controlling
terminal.
When you use the 'tty' command or redirect input in the 'run'
command, only the input _for your program_ is affected. The input for
GDB still comes from your terminal. 'tty' is an alias for 'set
inferior-tty'.
You can use the 'show inferior-tty' command to tell GDB to display
the name of the terminal that will be used for future runs of your
program.
'set inferior-tty [ TTY ]'
Set the tty for the program being debugged to TTY. Omitting TTY
restores the default behavior, which is to use the same terminal as
GDB.
'show inferior-tty'
Show the current tty for the program being debugged.