history builtin command can be used to display the command history:
- to display the entire command history, type
- if you're only interested in the last N entries, type
history | tail -N.
Its behavior can be changed via various local variables (see Variables below).
Ion's history file is located by default in
Unlike other shells, Ion by default saves repeated commands only once:
# echo "Hello, world!" Hello, world! # true # true # false # history echo "Hello, world!" true false
The following local variables can be used to modify Ion's history behavior:
The file into which the history should be saved. At Ion' startup, the history will be read from this file, and when it exits, the session's history will be appended to this file.
Whether the history should be read from/written into the file specified by
A value of
1 means yes, everything else means no.
The maximum number of lines kept in the history file when flushed from memory.
It is useless to set this to a higher value than
HISTORY_SIZE. Ideally, those variables
would have the same value, since this would otherwise result in loss of information on history
write to disk, which might not be worth it given the nowadays cheap hardware space.
Which commands should not be saved in the history.
[ no_such_command whitespace duplicates ]
Each element of the array can take one of the following options:
All commands are ignored, nothing will be saved in the history.
Commands which return
NO_SUCH_COMMANDwill not be saved in the history.
Commands which start with a whitespace character will not be saved in the history.
Where xxx is treated as a regular expression. Commands which match this regular expression will not be saved in the history.
All preceding duplicate commands are removed/ignored from the history after a matching command is entered.
Specifying an empty array, means that all commands will be saved.
You can specify as many elements as you want.
Any invalid elements will be silently ignored. They will still be present in the array though.
You can also specify as many regular expressions as you want (each as a separate element).
However, note that any command that matches at least one element will be ignored.
(Currently, ) there is no way to specify commands which should always be saved.
When specifying regex:-elements, it is suggested to surround them with single-quotes (
As all variables,
HISTORY_IGNOREis not saved between sessions. It is suggested to set it via ions init file.
let HISTORY_IGNORE = [ .. ]command itself is not effected except if the assignment command starts with a whitespace and the whitespace element is specified in this assignment.
See the following example:
# echo @HISTORY_IGNORE # let HISTORY_IGNORE = [ all ] # saved # let HISTORY_IGNORE = [ whitespace ] # saved # true # ignored # let HISTORY_IGNORE = [ ] # saved # let HISTORY_IGNORE = [ whitespace ] # ignored # history echo @HISTORY_IGNORE let HISTORY_IGNORE = [ all ] # saved let HISTORY_IGNORE = [ whitespace ] # saved let HISTORY_IGNORE = [ ] # saved
# let HISTORY_IGNORE = [ no_such_command ] # true # saved # true # saved # false # saved # trulse # ignored
# let HISTORY_IGNORE = [ 'regex:.*' ] # behaves like 'all' # true # ignored # true # ignored # false # ignored # trulse # ignored
I like to add
regex:#ignore$ to my
That way, whenever I want to ignore a command on the fly, I just need to add
#ignore to the
end of the line.
The maximum number of lines contained in the command history in-memory.
Ideally, this value should be the same as
HISTFILE_SIZE for details).
Whether a corresponding timestamp should be recorded along with each command.
The timestamp is indicated with a
# and is unformatted as the seconds since the unix epoch.
Possible values are
0 (disabled) and