Article - How to Clear Bash History on Linux

[TWPonKubuntu]

Long, long ago, I asked this of the forum and today, I found this simple set of commands:

https://www.howtoforge.com/clear-bash-history/

The article is very short but I quote from it:

To clear the Bash History on Linux, use this combination of 3 commands:

cat /dev/null > ~/.bash_history && history -c && exit

What do these commands do?

• The 'cat' command empties the .bash_history file of the currently logged in user.
• The 'history -c' command cleans the history of the current user session.
• The 'exit' command quits the current session.

I normally have a few commands in the bash history that I use daily, my "workhorse" commands. However, occasionally I will do a lot of bash commands and my daily set is pushed way down the list and it become time consuming to step back through the history. So then I clear the bash history and re-enter my daily workhorse commands.

Hopefully this will help you in a similar way.

[vinnywright]

What , clear the history . heavens NO , thats how I remember what I was up to last night , "clear the history" , crazy talk!

OK so amusement aside , nice post , that may be in order once in a wile

VINNY

[TWPonKubuntu]

Vinny: Two words: Postit Notes

'course I have to be able to read my handwriting from 3am notes...

[kubicle]

However, occasionally I will do a lot of bash commands and my daily set is pushed way down the list and it become time consuming to step back through the history.

Just in case you aren't aware of the functionality, searching through bash history should be less time consuming than stepping back through it (if you have a long history)...and also less time consuming than clearing your history and retyping the commands (once you run the searched commands, they'll be in recent history again).
https://www.digitalocean.com/communi...h-bash-history

[TWPonKubuntu]

kubicle, Yes, I do know how that works; the rotation of executed commands to the top of the history stack. Normally that works well, Except when I also do a session of lots of other bash commands. The history can get very long... say 50 or more commands during one or more sessions in Konsole/Terminal. It takes too long to manually scroll simply to find a couple of commands.

When I'm done with a long terminal session, I really like to flush the history and start over with a minimal few commands in history. As I said, I do have a set of about 3-4 commands that I run daily. No always together or I'd put them in a script file.

Hence the three bash commands in my original post, which could be put in a script file too...

[kubicle]

The history can get very long... say 50 or more commands during one or more sessions in Konsole/Terminal. It takes too long to manually scroll simply to find a couple of command.

I didn't mean manual scrolling through commands with the arrow keys...I meant searching the history using ctrl+r and type a few chars that are in your command to find the command you're looking for (subsequent ctrl+r will cycle through matches). It's very fast even if you have thousands of history entries.

[jlittle]

IMO your command line history is potentially very valuable. For years I have maintained a bunch of aliases and settings to manage this. Gradually, bash has improved its history facilities, but I've just recently concluded that my approach is inadequate. I wonder if there's people with ideas here that I could use.

Presently I have a separate history for four differently coloured konsoles, and use

HISTCONTROL=ignoredups
HISTIGNORE="&:h"
HISTSIZE=2000
HISTFILESIZE=421

but the only reason that I only save 420 entries, is that when the history number gets to 4 digits it's too long to type and takes up too much space when I list them; to do that I use:

alias h='history $((LINES*2)) | pr -2tw$COLUMNS'
alias ha='history | less +G'

Ideally I'd like to keep all history for years in a searchable form, but be able to reset the history number to something small when I want to.

Perhaps it's another hint that I really should be using zsh.

[kubicle]

Perhaps it's another hint that I really should be using zsh.

I can't tell how big a difference there is these days (haven't kept up with bash development), but better history options was one of the reasons I went zsh years ago (like the ability of sharing history with open sessions, timestamps etc.)...and haven't really looked back. (The biggest reason for switching was superior tab completion).

One of my latest zsh history discoveries is this one, which I find pretty neat: https://github.com/zsh-users/zsh-autosuggestions
(I also really like zsh-syntax-highlighting, even though it's not related to history.)

[TWPonKubuntu]

kubicle;

Ok, you're usage certainly exceeds my needs. I seldom use bash for more than a few commands, mostly related to updating my systems (I have more than one). I find that some GUI update managers (I use Linux Mint) do not report the same updates from the repositories as the command line does. So I check in Terminal/Konsole.

So, limited need for very large history, except in rare instances, and then I want to clear the history to return to my simpler set of commands.

[kubicle]

Ok, you're usage certainly exceeds my needs. I seldom use bash for more than a few commands, mostly related to updating my systems (I have more than one). I find that some GUI update managers (I use Linux Mint) do not report the same updates from the repositories as the command line does. So I check in Terminal/Konsole.

So, limited need for very large history, except in rare instances, and then I want to clear the history to return to my simpler set of commands.

I hear you, but ctrl+r can still be very useful and fast, even with just a few dozen lines of history.

And certainly faster than retyping your basic commands (after clearing your history)...of course, such a thing could easily be automated as well (rather than completely removing your history, you could replace it a file that only has your basic "command set" as history items). That way you wouldn't need to retype your commands after every "clearance".

[GreyGeek]

Riley's Believe It or Not!
In 20 years of using Linux I never heard of ctrl+r & ctrl+s to search through bash history.

I tried it a while ago. IF I am not doing something wrong I find it very awkward and clumsy to use, IMO. Every time I tried to ctrl+r for "mount /dev/sdc /backup" it gave me "I found 3740 ..." but to use it I had to continue typing the command to narrow the results.
It was a lot easier just to type the command. I frequently use the up arrow and find the desired command within seconds.

[kubicle]

I tried it a while ago. IF I am not doing something wrong I find it very awkward and clumsy to use, IMO. Every time I tried to ctrl+r for "mount /dev/sdc /backup" it gave me "I found 3740 ..." but to use it I had to continue typing the command to narrow the results.
It was a lot easier just to type the command.

The search works best if you search for a string that's distinctive. In your example, I'd probably search for "/backup" rather than "mount". (ctrl+r, then "/backup" and if finds a wrong match, press ctrl+r again to find the next match...chances are you'd find it pretty quickly).

Of course, the usefulness of the search depends greatly on the length of the command, some commands are quicker to type than to search.

I frequently use the up arrow and find the desired command within seconds.

That works well if you have used the command recently, but no one really wants to press the up arrow for 500 times to reach a command they used a month back

[TWPonKubuntu]

That works well if you have used the command recently, but no one really wants to press the up arrow for 500 times to reach a command they used a month back

My point, exactly.

I'd like to see an option to display the history cache as a pulldown selection item which I could scroll while reading each command, in the sequence that each was used.

[Rod J]

I've used this modification to .bashrc for years:

# enable command line history recall navigation filtering by using up and down arrows like in 4dos/NT/TC 
bind '"\e[A"':history-search-backward
bind '"\e[B"':history-search-forward

# This gives the equivalent 4Dos/NT/TC Page-Up command to show all previous entered commands based
# on the partial input on the current line
bind '"\e[5~"':"\"\C-k\C-ahistory | grep '^ *[0-9]* *\C-e.'\C-m\""

I was a big fan of 4Dos back in my DOS days. The above gives a very similar function to what 4Dos could do.

You just type one or more letters of the command(s) you are looking for and each matching command will appear. Just keep typing up or down arrows or add more characters to find the one you're looking for.

The second mod allows you to see all previous commands based on a partial input line. I don't use this one so much myself as I've forgotten how to make more use of the list.

[TWPonKubuntu]

Thanks Rod