History command inside bash script

Question

History is a shell-built in command I couldn't able to use that within a BASH script. So, Is there a way attain this using BASH script ?
Here we go my script for you:

#!/bin/bash
history |  tail -100 > /tmp/history.log
cd /tmp
uuencode history.log history.txt  | mail -s "History log of server" hello@hel.com

Answer 1

Bash disables history in noninteractive shells by default, but you can turn it on.

#!/bin/bash
HISTFILE=~/.bash_history
set -o history
history | tail …

But if you're trying to monitor activity on that server, the shell history is useless (it's trivial to run commands that don't show up in the history). See How can I log all process launches in Linux.

If you're debugging a script then shell history is not the best way to get useful information. A much better tool is the debug trace facility: put set -x near the top of the script. The trace is written to standard error.

Answer 2

I'm not sure if it actually uses the history capability when running non-interactively, otherwise every shell script you run would clutter up your command history.

Why not go directly to the source ${HOME}/.bash_history, replace history | tail -100 with tail -100 ${HOME}/.bash_history. (If you use timestamps you'd probably have to do something along the lines of grep -v ^# ${HOME}/.bash_history | tail -100).

Answer 3

If you want to use the output of the history command from an active shell session in a script, you can use an alias to run the command first. Then, in the same alias, you can call the remainder of the script. With such a configuration, you can achieve essentially the same result as having the history command in the actual script.

For instance, you can create an alias like this, assuming the script's name is script.sh:

alias hy_tmp='history | tail -100 > /tmp/history.log ; bash /patch/to/script.sh'

And change the script to this:

#!/bin/bash
cd /tmp
uuencode history.log history.txt  | mail -s "History log of server" hello@hel.com

I found this question while writing a process to combine, sort and synchronize ~/bash_history files on two computers so it'll be easy to search commands I've used in the past.

It's much less of a hassle to update my cumulative history file without having to log into a new shell to have ~/bash_history updated. For monitoring a server this will obviously not work, as mentioned in the other answers.

My usage in particular is:

alias hbye='history | cut -c 8- > /home/chris/.bash_history_c; bash /hby.sh

The script hby.sh then pulls all unique entries from all ~/.bash_history* files.

Answer 4

The history builtin seems to be disabled inside a shell script. See here: http://www.tldp.org/LDP/abs/html/histcommands.html

I have not found any official documentation about this.

Answer 5

Create a script named script.sh as below. It creates a script named X and puts Y Number of lines of your history into it.

#!/bin/bash
SCRIPT_NAME=$1
NUMBER_OF_LINES_BACK=$2

# Enable History in a non interactive shell
HISTFILE=~/.bash_history
set -o history

# echo shabang line and x number of lines of history to new script
echo \#\!\/bin\/bash > $SCRIPT_NAME.sh; history | tail -n $NUMBER_OF_LINES_BACK >> $SCRIPT_NAME.sh;
chmod u+x $SCRIPT_NAME.sh;

# Open the newly created script with vim
vim $SCRIPT_NAME.sh;
~

Then if you want to create a script to a accomplish a task named "task" that you have been working on for the last 14 lines run

script.sh task 14

Then clean up your history to make a nice script!

Answer 6

The history command is disabled by default on bash script that's why even history command won't work in .sh file. for its redirection, kindly redirect bash_history file inside the .sh file.

or history mechanism can be enabled also by mentioning history file and change run-time parameters as mentioned below

#!/bin/bash
HISTFILE=~/.bash_history
set -o history 

note: mentioned above two lines on the top of the script file. now history command will work in history.

Answer 7

Every user have it's own history file which is result of history command.Instead of using history command in your shell script you can use history file for user. There will be a .bash_history file in home directory of user, that will be the history file for the user.

Answer 8

Short answer:

use history -p to perform history expansion explicitly.

An example follows.

One use case happens a lot for me is:

• previous command get a list of file names, and print to stdout,
• I need to edit those file with vim.

Since my bash has been set -o histexpand, usually what I did is typing

vim $(!!)

to edit those files listed by previous command.

Sadly sometimes mistake happens, so I enable verify by shopt -s histverify.

Now I can verify the expansion, with cost of one extra Return key.

Today I want to wrap those details into a bash function since I use them a lot,

function vk() {
    set -o history && set -o histexpand;
    vim -i ~/.viminfok $($(history -p !!));
}

Here I use two nested command substitution, the inner one to expand !! to previous command, the outer one to execute it and get the output.

Now I can achieve the same effect, with only three key, and one of those is Return!