如何使用 shell 命令在 GDB 中设置环境变量？

Question

I want to run gdb with only a single variable MyVar in its environment.

However, the variable's contents are rather complex, containing non-printable ASCII, and so is best set using eg MyVar=$(python -c 'print("\\xff...")') .

I'm left with two options:

1. Set the MyVar in bash before running gdb . Then inside gdb , remove all other environment variables individually using unset environment NAME ( very tedious! ).

2. Clear all environment variables using unset environment . Then inside gdb , set MyVar using a shell command (as above) ( how?)

Any ideas?

Answer 1

Option 2 is possible .

(gdb) unset environment
(gdb) python gdb.execute("set environment Myvar=\xff")
(gdb) show environment 
Myvar=ÿ

Option 1 can be done with env(1) .

$ env -i MyVar=$(python -c 'print("xyz")') gdb
(gdb) show environment
MyVar=xyz
LINES=35
COLUMNS=80

Then you just have to clear LINES and COLUMNS.

Answer 2

When starting gdb from shell command-line, you can specify which program to run, with which arguments (with --args ) , and even modify the environment of the program with the help of env !

I just did it successfully like this:

gdb --ex=run --args env LD_BIND=now LD_DEBUG=libs \
apt-get install --yes $(cat pkgs-to-install-to-crash-apt)

--ex=run is to ask gdb to run it immediately.

In your case, you would do env -i .

It differs from the suggested env -i VAR=... gdb program in that only your examined program is under the special environment, but not gdb.