Time-saving Bash Techniques
If you are a nerd and love hacking away at your UNIX-like machine’s command line, then chances are you know that things can get really repetitive very quickly. One of my pet peeves is changing-directory upwards towards the root directory by typing cd ../../ or some such command. Some people alias two dots to the cd command to go up one level, 3 dots to go up 3 levels, or whatever. To me this is clunky. I wanted something more flexible. So up was born. up is a Bash function that takes one argument: the number of directories you want to go up. If you do not specify an argument, up will take you up one directory.
So if you are at /this/really/deep/directory/looking/around, instead of typing lots of dots and slashes to get to /this/really/deep, just type up 3. Simple and Quick. Unless you are really, really deep, you’ll probably only ever have to type a maximum of 5 keystrokes to go up to any level, whereas with cd, you’ll have to type ../ as many times as levels you want to go up. That’s at least 6 (5 if you leave off the trailing slash) if you want to go up only one level. There’s some Big-O notation just waiting to happen from that scenario.
Check out the code:
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| #! /bin/bash | |
| function up () { | |
| levels=$1 | |
| if [ -z "$levels" ]; then | |
| levels=1 | |
| fi | |
| # Test if $levels is a number; the -eq operator expects a number, and will | |
| # output an error if one is not found. Any output the STDERR is redirected | |
| # to the bit bucket (/dev/null) | |
| if [ "$levels" -eq "$levels" ] 2> /dev/null; then | |
| if [ "$levels" -eq "0" ]; then | |
| levels=1 | |
| fi | |
| for (( c=1; c<=levels; c++ )) | |
| do | |
| cd ../ | |
| done | |
| else | |
| echo up: expected a number, not $levels | |
| fi | |
| } |
Include that in your .bashrc.
Very simple, but not without its problems. If you use the cd - command to go to the last directory you were in, this will break that because it cds multiple times. A solution to that is to build a string with the corresponding number of ../ entries you want to go up, then passing that as an argument to cd. I am sure there are more problems, and if you want to contribute to the betterment of nerdkind by improving the function, please fork my gist and issue a pull-request.
Jacob Degeling 