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Appending a line to a file only if it does not already exist
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This actually doesn't work when the line starts with a -.
– hyperknot
Feb 6 '18 at 22:03
1
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How to search a string in multiple files and return the names of files in Powershell?
... large operations like that. It becomes very convoluted when you try to do all of that on one line and it is very easy to make a large mistake. I speak from experience
– Kolob Canyon
Sep 6 '18 at 15:44
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URL encoding the space character: + or %20?
...he server in an HTTP request message using method GET or POST, or, historically, via email. The encoding used by default is based on a very early version of the general URI percent-encoding rules, with a number of modifications such as newline normalization and replacing spaces with "+" instead of "...
StatusbarTools 扩展 - 状态栏自定义工具 · App Inventor 2 中文网
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故障排除
常见问题
Q: 状态栏颜色设置无效？
A: 检查应用是否具有必要的权限，某些设备需要额外的设置。
Q: 图标颜色不改变？
A: 确保使用正确的参数值（”Light” 或 “Dark”），检查设备...
How do I limit the number of returned items?
...ith exec() instead. Therefore, with the mongoose 3.8.1 you'd do this:
var q = models.Post.find({published: true}).sort({'date': -1}).limit(20);
q.exec(function(err, posts) {
// `posts` will be of length 20
});
or you can chain it together simply like that:
models.Post
.find({published: tr...
How to use Git and Dropbox together effectively?
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I think that Git on Dropbox is great. I use it all the time. I have multiple computers (two at home and one at work) on which I use Dropbox as a central bare repository. Since I don’t want to host it on a public service, and I don’t have access to a server that I can ...
Easiest way to check for an index or a key in an array?
... associative array)
[ ${array[key]+abc} ] && echo "exists"
Basically what ${array[key]+abc} does is
if array[key] is set, return abc
if array[key] is not set, return nothing
References:
See Parameter Expansion in Bash manual and the little note
if the colon is omitted, the ope...
Get last n lines of a file, similar to tail
... blocks.append(f.read(BLOCK_SIZE))
else:
# file too small, start from begining
f.seek(0,0)
# only read what was not read
blocks.append(f.read(block_end_byte))
lines_found = blocks[-1].count('\n')
lines_to_go -= lines_found
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Java string to date conversion
...tern seems valid.
Here's an extract of relevance from the javadoc, listing all available format patterns:
Letter Date or Time Component Presentation Examples
------ ---------------------- ------------------ -------------------------------------
G Era designator Text ...
How to create named and latest tag in Docker?
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Clean up commands:
Docker 1.13 introduces clean-up commands. To remove all unused containers, images, networks and volumes:
docker system prune
or individually:
docker container prune
docker image prune
docker network prune
docker volume prune
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