In addition to Idan answer, I want to add that alias precmd 'history -S; history -M' potentially can mess up the history file, since it also records SIGINT and EOF signal (Ctrl+C and Ctrl+D).

A better way would be save and merge current shell history before running a command, and save after a comment.

You can achieve it by this setup below instead, because the tcsh doesn't recognize SIGINT or EOF as a command.

alias precmd        "history -M"
alias postcmd       "history -S"

In addition to Idan answer, I want to add that alias precmd 'history -S; history -M' potentially can mess up the history file, since it also records SIGINT and EOF signal (Ctrl+C and Ctrl+D).

A better way would be save and merge current shell history after running a command.

You can achieve it by this setup below instead, since the tcsh doesn't recognize SIGINT or EOF as a valid command.

alias postcmd       "history -S; history -M"