Using Bash History More Efficiently: HISTCONTROL
Using the HISTCONTROL variable you can control how bash stores your command history. You can tell it to ignore duplicate commands and/or to ignore commands that have leading whitespace.
When working at the command line we often end up executing some commands multiple times. The default history size is 500, too many duplicates of the same commands can fill up your history and leave you with a less then useful history. You can of course increase the size of your history list using HISTSIZE or HISTFILESIZE.
Another alternative is to tell bash not to store duplicates. This is done with the HISTCONTROL variable. HISTCONTROL controls how bash stores command history. Currently there are two possible flags: ignorespace and ignoredups. The ignorespace flag tells bash to ignore commands that start with spaces. The other flag, ignoredups, tells bash to ignore duplicates. You can concatenate and separate the values with a colon, ignorespace:ignoredups, if you wish to specify both values, or you can just specify ignoreboth.
You can set the flags in your ~/.bashrc file or in the global /etc/bash.bashrc file. The following command would append it to your ~/.bashrc file:
$ echo "HISTCONTROL=ignoreboth" >>~/.bashrc
Now logout and login, type some commands, try the same command numerous times. Now check your history using the up arrow or do:
You shouldn't see any duplicates in your history.
The history control option, ignorespace, is useful for executing commands that you don't want to record in your command history.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- Petros Koutoupis' RapidDisk
- ServersCheck's Thermal Imaging Camera Sensor
- The Italian Army Switches to LibreOffice
- Linux Mint 18
- Oracle vs. Google: Round 2
- The FBI and the Mozilla Foundation Lock Horns over Known Security Hole
- Privacy and the New Math
- Firefox 46.0 Released
Until recently, IBM’s Power Platform was looked upon as being the system that hosted IBM’s flavor of UNIX and proprietary operating system called IBM i. These servers often are found in medium-size businesses running ERP, CRM and financials for on-premise customers. By enabling the Power platform to run the Linux OS, IBM now has positioned Power to be the platform of choice for those already running Linux that are facing scalability issues, especially customers looking at analytics, big data or cloud computing.
￼Running Linux on IBM’s Power hardware offers some obvious benefits, including improved processing speed and memory bandwidth, inherent security, and simpler deployment and management. But if you look beyond the impressive architecture, you’ll also find an open ecosystem that has given rise to a strong, innovative community, as well as an inventory of system and network management applications that really help leverage the benefits offered by running Linux on Power.Get the Guide