diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 27 |
1 files changed, 25 insertions, 2 deletions
@@ -72025,9 +72025,32 @@ option isn't present. The history is maintained in a text file called .code .txr_history in the user's home directory. Whenever the interactive listener terminates, -this file is overwritten with the history contents stored in the listener's +this file is updated with the history contents stored in the listener's memory. The next time the listener starts, it first re-loads the history from -this file, making the commands of a previous session available for recall. +this file, making the most recent +.code *listener-hist-len* +expressions of a previous session available for recall. + +The history file is maintained in a way that is somewhat +robust against the loss of history arising from the situation that a user +manages multiple simultaneous \*(TX sessions. When a session terminates, it +doesn't blindly overwrite the history file, which may have already been updated +with new history produced by another session. Rather, it appends new entries +to the history file. New entries are those that had not been previously read +from the history file, but have been newly entered into the listener. + +An effort is made to keep the history file trimmed to no more than +twice the number of entries specified in +.codn *listener-hist-len* . +The terminating session first makes a temporary copy of the existing +history, which is trimmed to the most recent +.code *listener-hist-len* +entries. New entries are then appended to this temporary file. +Finally, the actual history file is replaced with this temporary file by a +.code rename-path +a rename operation. This algorithm doesn't use locking, and is therefore not +robust against the situation when a two or more multiple interactive \*(TX +sessions belonging to the same user terminate at around the same time. The home directory is determined from the contents of the |