Erasing shell history or system logs

Holds a command that erases the record of what ran: history -c / -w, unset HISTFILE, HISTFILE=/dev/null, HISTSIZE=0, set +o history, PowerShell's Clear-History; deleting or truncating a *_history file (rm, truncate, shred, : >); journalctl --vacuum-time / --vacuum-size / --vacuum-files / --rotate; rm -rf, truncate or shred against /var/log; and git reflog expire --expire=now or git gc --prune=now, which drop the safety net a history rewrite would otherwise leave. A READ is not matched: history on its own, history | tail, journalctl --since, git reflog, git reflog show, and a plain git gc. MISSES HISTFILE unset in a shell profile rather than at the prompt, a log truncated with an editor or a file tool, and a purge run by a tool other than these. A global flag between git and reflog/gc is tolerated (git -C <dir> reflog expire …, --no-pager, -c k=v), and an absolute tool path such as /usr/bin/git still matches; a flag that itself runs a program is not read. A quoted MENTION is not a use: a search, a git commit -m message, an echo or a curl --data body that only names this command is left alone. That holds only while every shell metacharacter stays inside the quotes, so git commit -m "x" && … is still caught; and the carrier must be the first word, so sudo grep … is not exempt.