Using Bash History More Efficiently
If you've used bash for a while you probably know that the commands you enter are saved in the file ~/.bash_history when you log out. Next time you log in, bash automatically loads these history commands from the saved file and you can then use the up and down arrow keys to browse your command history and find the command you want rather than re-entering it.
However, there are more effective ways to use bash's history: you can use Ctrl+R (Control key held down at the same time as the R key). This will display the following in your shell:
If you know type some substring found in the command you're searching for, for example "ls", bash will search for matching commands. For example, it might show:
(reverse-i-search)`ls': lsof -nP -p 3930
What it actually shows is going to be dependent on the commands you've previously entered.
When you do this, bash looks for the last command that you entered that contains the substring "ls", in my case that was "lsof ...". If the command that bash finds is what you're looking for, just hit Enter to execute it. You can also edit the command to suit your current needs before executing it (use the left and right arrow keys to move through it). If you're looking for a different command, hit Ctrl+R again to find a matching command further back in the command history. You can also continue to type a longer substring to refine the search, since searching is incremental.
Note that the substring you enter is searched for throughout the command, not just at the beginning of the command.
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July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
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