Posted in Code, Linux/Unix on 22nd June 2009, 10:17 pm by Stuart
There’s a nice feature of BASH which is to use a comma delimited list of strings inside of curly braces to reduce the amount of typing:
here’s an example of using brace expansion to create log files for apache:
sudo touch {access,error}.log
Something seen less often is a blank entry like so:
cp foo{,.bck}
Which is shorthand for cp foo foo.bck. This is really useful when copying and moving files around using long paths. Using brace expansion can minimise the amount of typing and help avoid errors caused by typos too.
Another use of brace expansion since BASH v3.0 is the possibility of using ranges within the lists like so:
for foo in {1..10}
> do
> echo $foo
> done
1
2
3
4
5
6
7
8
9
10
Or alternatively with letters too:
echo {a..f}
a b c d e f
See the advanced bash scripting guide for more examples.
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Posted in Code, Linux/Unix on 22nd June 2009, 9:50 pm by Stuart
This .vimrc snippet highlights lines when you exceed 77 columns - this is especially useful if you are trying to adhere to PEP8 with Python development.
The if statement makes this work for older vims as well as more recent versions which is handy if you put your .vimrc on remote boxes as vim below v7.1.40 doesn’t have the matchadd function.
" Highlight lines over 77 columns
if has('matchadd')
:au BufWinEnter * let w:m1=matchadd('Search', '\%<81v.\%>77v', -1)
:au BufWinEnter * let w:m2=matchadd('ErrorMsg', '\%>80v.\+', -1)
else
:au BufRead,BufNewFile * syntax match Search /\%<81v.\%>77v/
:au BufRead,BufNewFile * syntax match ErrorMsg /\%>80v.\+/
endif
To configure highlighting to work manually see the vim wiki for more details http://vim.wikia.com/wiki/Highlight_long_lines
Whilst I’ve often heard people snub the PEP8 recommendation for keeping line length to under 79 chars, I’ve personally found it leads to more readable code whether you live in a terminal or use gui editors. YMMV
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Posted in Linux/Unix on 6th June 2009, 10:24 am by Stuart
I always forget this one, but it’s dead handy as it allows you to type “py” hit tab and it will auto complete for “Python” or “python” for example. Without this setting you’d have to type explicitly what you want. To enable run:
echo set completion-ignore-case on | sudo tee -a /etc/inputrc
tee -a appends to the file - though clearly proceed with caution and if in any doubt backup /etc/inputrc first.
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