> And noticed that $BASH_COMMAND always expanded to: > > read -p "[...:...] $BASH_COMMAND? > > where the ...:... is the expanded value of $BASH_SOURCE:$LINENO.
Err, sorry about that. I misremembered. It is actually expanding to read -p "[$BASH_SOURCE:$LINENO] $BASH_COMMAND" as it would normally do when used outside of a trap. The rest of the issue is still valid. On 04/11/2021, Emanuele Torre <torreemanue...@gmail.com> wrote: > Configuration Information [Automatically generated, do not change]: > Machine: x86_64 > OS: linux-gnu > Compiler: gcc > Compilation CFLAGS: -march=x86-64 -mtune=generic -O2 -pipe -fno-plt > -DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/bin' > -DSTANDARD_UTILS_PATH='/usr/bin' -DSYS_BASHRC='/etc/bash.bashrc' > -DSYS_BASH_LOGOUT='/etc/bash.bash_logout' > -DNON_INTERACTIVE_LOGIN_SHELLS > uname output: Linux t420 5.10.75-1-lts #1 SMP Wed, 20 Oct 2021 > 11:02:09 +0000 x86_64 GNU/Linux > Machine Type: x86_64-pc-linux-gnu > > Bash Version: 5.1 > Patch Level: 8 > Release Status: release > > Description: > BASH_COMMAND does not expand to the expected value when used in a > subshell inside a trap. > > I tried using the following DEBUG trap that i got from > http://mywiki.wooledge.org/BashGuide/Practices in bash-5.1: > > trap '(read -p "[$BASH_SOURCE:$LINENO] $BASH_COMMAND?")' DEBUG > > And noticed that $BASH_COMMAND always expanded to: > > read -p "[...:...] $BASH_COMMAND? > > where the ...:... is the expanded value of $BASH_SOURCE:$LINENO. > > Then I tried to use the same trap in bash-4.4 and it worked as > expected. > > Repeat-By: > > $ cat test1 > trap 'echo "$BASH_COMMAND"' DEBUG > echo hello > $ cat test2 > trap '(echo "$BASH_COMMAND")' DEBUG > echo hey > bash > > $ ./bash test1 # bash-4.4 > echo hey > hey > $ ./bash test2 # bash-4.4 > echo hey > hey > $ bash test1 # bash-5.1 > echo hey > hey > $ bash test2 # bash-5.1 > echo "$BASH_COMMAND" > hey > > $ ./bash --version | head -1 > GNU bash, version 4.4.0(3)-release (x86_64-unknown-linux-gnu) > $ bash --version | head -1 > GNU bash, version 5.1.8(1)-release (x86_64-pc-linux-gnu) >
