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el_gallo_azul
Asked: 2018-09-17 18:28:43 +0800 CST

Command history seems to be missing the first 75 lines

  • 772

A couple of years ago, I did the automatic distribution update from 14.04 to 16.04. For the first time in my life, I was able to continue to use the computer after the automatic distribution update. As usual, the software repositories are all muntered, so system updates don't work properly, but I've gotten by.

I am going to do a clean installation of 18.04, however. In order to be able to configure my system more easily after the installation, I exported my command history to a text file.

$ history > /.../20180915_Command_history.txt

Beautifully, the resulting text file contains line numbers. Somewhat mysteriously, the first line number is 76. After looking at the first few lines, it looks like there were probably some previous commands.

  1. Do the line numbers just start at 76 for some reason?
  2. If not, is there any way that I can see lines 1 to 75?
command-line bash bashrc history bash-history

1 Answers

  1. Best Answer

    First of all, If you need to get a backup of your command line history, then just copy this file:

    ~/.bash_history

    Remember that you have to close all your terminals or run history -a to append all commands from those history sessions to the history file.

    If not, is there any way that I can see lines 1 to 75?

    Every command that has been saved in your history is available at ~/.bash_history file, to see all of them open a terminal and run:

    cat ~/.bash_history

    To get an output similar to history command with numbering run:

    cat -n ~/.bash_history

    Do the line numbers just start at 76 for some reason?

    Run this command:

    grep "^HIST" .bashrc

    You have to get an output similar to:

    HISTSIZE=1000
HISTFILESIZE=2000

    As I said before ~/.bash_history keeps command-line's history.

    • The HISTFILESIZE show how many command should ~/.bash_history keeps track of, for mine it's 2000.

    • And HISTSIZE is the number of commands that history command (shell built-in actually) keeps track of.

    When you open a terminal and run history, it will picks the last HISTSIZE number of commands from ~/.bash_history and shows that to you.

    If you run new commands it will remove the older ones from session and append the new ones at the end of its list so the number of commands will match HISTSIZE.

    I guess while asking the question you had 74 command more than of HISTSIZE in your .bash_history and that's the reason why it starts at 75.

    From man bash:

    • HISTSIZE

      The number of commands to remember in the command history.

    • HISTFILESIZE

      The maximum number of lines contained in the history file.

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