Is it possible to save `bc` command line history?

If you aren't happy with the command line editing features that are built into a program, you can run it through rlwrap. This is a wrapper around a command line processor (a REPL) that lets you edit each line before it's sent. Rlwrap uses the readline library and saves history separately for each command.

Running rlwrap bc won't do anything for you because rlwrap detects that your bc wants to do its own command line editing, so rlwrap turns itself off. Since you do want rlwrap's command line editing features and not the underlying command's, run

rlwrap -a bc

The command history will be saved in ~/.bc_history.

The main downside of relying on rlwrap rather than using the program's own readline integration is that rlwrap can't do any context-sensitive completion. For example, the python toplevel completes known variables and fields, but rlwrap python cannot do that. Since bc doesn't appear to have any custom completion, rlwrap -a bc doesn't lose functionality over bc.

This method with tee works for me. It saves the whole dialogue.

$ rm -i bc.log; tee -a bc.log | bc | tee -a bc.log
rm: remove regular file 'bc.log'? y
3*4
12
9*16
144
^C
$ cat bc.log    
3*4
12
9*16
144
$ 

You could also have separate log files for the input and output of bc.

The next example shows how only the input is saved, and appended between sessions.

$ rm bc.log  # only when you want to clear the log file

$ tee -a bc.log | bc
7+5-2
10
37*27
999
225/3
75
^C
$ cat bc.log
7+5-2
37*27
225/3
$ tee -a bc.log | bc
2^10
1024
^C
$ cat bc.log
7+5-2
37*27
225/3
2^10
$