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Day 22 - The OSI Model - Basics

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michaelcade
2022-01-21 08:24:45 +00:00
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@ -87,6 +87,27 @@ If you have a long complex configuration file and you want or need to find somet
If you are like me and you use that `clear` command a lot then you might miss some of the commands previously ran, we can use `history` to find out all those commands we have run prior. `history -c` will remove the history.
When you run `history` and you would like to pick a specific command you can use `!3` to choose the 3rd command in the list.
You are also able to use `history | grep "Command` to search for something specific.
On servers to trace back when was a command executed, it can be useful to append the date and time to each command in the history file.
The following system variable controls this behaviour:
```
HISTTIMEFORMAT="%d-%m-%Y %T "
```
You can easily add to your bash_profile:
```
echo 'export HISTTIMEFORMAT="%d-%m-%Y %T "' >> ~/.bash_profile
```
So as useful to allow the history file grow bigger:
```
echo 'export HISTSIZE=100000' >> ~/.bash_profile
echo 'export HISTFILESIZE=10000000' >> ~/.bash_profile
```
![](Images/Day15_Linux21.png)
Need to change your password? `passwd` is going allow us to change our password. Note that when you add your password in like this when it is hidden it will not be shown in `history` however if your command has `-p PASSWORD` then this will be visible in your `history`.