Why is bash not storing commands that start with spaces?

Question

If I perform a sequence of commands like:

$ ls
$ grep abc file.txt

and then use the up arrow key to get the previous one, the terminal will show the last cmd (which is the grep here)

But if I do something like this:

$ ls
$   grep abc file.txt

where grep is preceded by spaces, pressing up gives ls, not grep.

Why is this?

Follow-up: Why does bash have a HISTCONTROL=ignorespace option? — Gilles 'SO- stop being evil', Feb 19 '14 at 23:39

score 99 · Accepted Answer · edited Jul 27 '22 at 19:39

99

echo $HISTCONTROL
ignoreboth

If you want to change this behaviour add a new line to your ~/.bashrc file (which will affect every new shell you open):

HISTCONTROL=ignoredups

(assuming you still want to filter out duplicates)

man bash:

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.

edited Jul 27 '22 at 19:39

redseven

592

answered Feb 19 '14 at 15:15

Hauke Laging

90,279

4

and HISTCONTROL is set to ignoreboth in the default ~/.bashrc provided by debian at least. – Stéphane Chazelas Feb 19 '14 at 15:15
2

What is the use case of ignorespace? – Ciro Santilli OurBigBook.com Sep 28 '15 at 14:30
2

In Ubuntu 14.04 the default is ignoreboth which is kind-of annoying. – Nick Gammon May 09 '16 at 08:01
14

Ciro, I assume it's so that you can enter command like echo "drop database mydb" | mysql -u root -pPassword and not have it saved in history. – Jeremy May 30 '16 at 01:04
@Jeremy yes, that seems like a legitimate use case – code_monk Nov 23 '17 at 15:10
2

For mac users, HISTCONTROL is not set to anything, so you'll need to add it to your bash_profile or similar - https://unix.stackexchange.com/questions/115917/why-is-bash-not-storing-commands-that-start-with-spaces – chrismarx Dec 26 '18 at 19:00

ma1band · Answer 2 · 2022-12-19T00:06:17.143

-2

Add the line HISTCONTROL=ignoredups to ~/.bashrc (or /.bash_profile) then, from the command line, run source ~/.bashrc (or /.bash_profile) to implement the changes to the current shell session

edited Dec 19 '22 at 00:06

answered Dec 19 '22 at 00:04

ma1band

1

3

This duplicates the accepted answer. – G-Man Says 'Reinstate Monica' Dec 19 '22 at 05:56

Why is bash not storing commands that start with spaces?

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