How do I prevent commands from showing up in Bash history?

Question

Sometimes, when I run commands like rm -rf XYZ, I don't want this to be recorded in Bash history, because I might accidentally run the same command again by reverse-i-search. Is there a good way to prevent this from happening?

Selah

serverfault.com/questions/48769/… – Thissa

While bash may be used for writing shell scripts (hence programming), this particular aspect of it has absolutely nothing to do with programming (history is an interactive-only thing). Voting to close. – Bradeord

Related: Execute command without keeping it in history – Headliner

Answer 1

If you've set the HISTCONTROL environment variable to ignoreboth (which is usually set by default), commands with a leading space character will not be stored in the history (as well as duplicates).

For example:

$ HISTCONTROL=ignoreboth
$ echo test1
$  echo test2
$ history | tail -n2
 1015  echo test1
 1016  history | tail -n2

Here is what man bash says:

HISTCONTROL

A colon-separated list of values controlling how commands are saved on the history list. If the list of values includes ignorespace, lines which begin with a space character are not saved in the history list. A value of ignoredups causes lines matching the previous history entry to not be saved. A value of ignoreboth is shorthand for ignorespace and ignoredups. A value of erasedups causes all previous lines matching the current line to be removed from the history list before that line is saved. Any value not in the above list is ignored. If HISTCONTROL is unset, or does not include a valid value, all lines read by the shell parser are saved on the history list, subject to the value of HISTIGNORE. The second and subsequent lines of a multi-line compound command are not tested, and are added to the history regardless of the value of HISTCONTROL.

See also:

• Why is bash not storing commands that start with spaces? at unix SE
• Why does bash have a HISTCONTROL=ignorespace option? at unix SE

Berley

Answer 2

In your .bashrc/.bash_profile/wherever you want, put export HISTIGNORE=' *'. Then just begin any command you want to ignore with one space.

$ ls  # goes in history
$  ls # does not

Bunny

This depends on the value of the HISTCONTROL environment variable, which does not necessarily have ignorespace set. – Derick

If HISTCONTROL contains ignorespace, it's actually only redundant to include ` *` in HISTIGNORE. The two operate independently. – Microgamete

Answer 3

Even better use HISTIGNORE. This allows you to specify a set of patterns to be ignored (such as rm). It is better (I think) than just piping all history to /dev/null.

Isobelisocheim

Ah yes, forgot about that one :) – Delindadelineate

Answer 4

kill -9 $$

I know that is not as best as the previous answers, but this will kill the current Bash shell without saving anything, useful when HISTCONTROL is not set by default, you forgot to set it, or pure and simple you forgot to put a leading space and you just typed in some passwords and don't want them to remain permanently in history.

This is the quick way, and something like erasing the history file is not as good because you need to do it outside a history saving shell (log in as different user and use su/sudo, creating a background job, etc.)

Belleslettres

Answer 5

You can do one of two things:

export HISTFILE=/dev/null

Or, begin the command with a space.

Delindadelineate

a space before that's awesome – Courante

Some of us think auto-ignoring commands prefixed by a space is a really bad idea and therefore don't have ignorespace set by default. – Derick

Setting HISTFILE this way prevents storing any history, and does not prevent the command from being added to the in-memory history. – Microgamete

Answer 6

Or

unset HISTFILE

(similar to the previous answer only shorter: export HISTFILE=/dev/null)

Heriberto

This only affects the on-disk history, not the in-memory history. – Microgamete

Answer 7

I added an "Incognito" functionality to my .bashrc for when I want to run some commands without being saved without having to add spaces before each one.

Do note though that the in-memory history of the current terminal session will still be saved, but when I open a new terminal the commands issued in a past terminal's incognito session will never be seen because they were never written to the HISTFILE.

To your .bashrc:

ignoreHistory="false"
DEFAULT_HISTFILE=~/.bash_history
HISTFILE="$DEFAULT_HISTFILE"

# Toggle incognito mode
incognito() {
    if [[ "$ignoreHistory" == "true" ]]; then
        echo -e "\e[33mExited incognito mode\e[39m"
        ignoreHistory="false"
        HISTFILE="$DEFAULT_HISTFILE"
    else
        echo -e "\e[33mEntered incognito mode\e[39m"
        ignoreHistory="true"
        HISTFILE=/dev/null
    fi
}

Nice little utility I think some people may find use in, you can even change the prompt to reflect whether you're in incognito mode or not.

Cassey

When toggling back, it seems that the whole history still gets written... even the commands you wrote just after entering incognito mode. At least that is what's happening when using zsh (I had to replace .bash_history with .zsh_history in your code). So I would avoid witching back to non incognito until closing the window or simply delete the else branch. – Keeter

to make the toggle back work, probably want to track the number of commands entered (using $HISTCMD or $LINENO, depending on the settings) and then use history -d <offset> to delete the lines. Or just use history -c and wipe the whole list from memory. – Envelopment

would exec $SHELL be a good 'exit incoginto' method here? – Teresiateresina

Answer 8

At shell startup, I explicitly cleanup the history from the entries that I don't want to be there. For example, I don't want any rm -rf in the history (it's trauma after removing a directory full of results processed overnight, just with a single Arrow-Up + Enter :)

I put the following snippet in my init file (works with .zshrc, should also work with .bashrc)

# ...
HISTFILE=~/.zshhistory
# ...

# remove dangerous entries from the shell history
temp_histfile="/tmp/$$.temp_histfile"
grep -v -P '^rm .*-rf' $HISTFILE > $temp_histfile
mv $temp_histfile $HISTFILE

Grouchy