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unix - head AND tail of file
... file.txt
And if you need to uses pipes for some reason then like this:
cat file.txt | (head; tail)
Note: will print duplicated lines if number of lines in file.txt is smaller than default lines of head + default lines of tail.
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Confused about stdin, stdout and stderr?
... Because those aren't technically files. They're device nodes, indicating a specific device to write to. UNIX may present everything to you as a file abstraction but that doesn't make it so at the deepest levels.
– paxdiablo
Aug 2 '10 at 5:44
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array_push() with key value pair
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So what about having:
$data['cat']='wagon';
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Commenting in a Bash script inside a multiline command
...ble to put comment lines in between your commands
# output MYSQLDUMP file
cat ${MYSQLDUMP} | \
# simplify the line
sed '/created_at/d' | \
# create some newlines
tr ",;" "\n" | \
# use some sed magic
sed -e 's/[asbi]:[0-9]*[:]*//g' -e '/^[{}]/d' -e 's/""//g' -e '/^"{/d' | \
# more magic
sed -n -e '...
How can I find the version of the Fedora I use?
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cat /etc/issue
Or cat /etc/fedora-release as suggested by @Bruce ONeel
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Why do we use __init__ in Python classes?
...init__. You can think of them as noting things into the Dog's birth certificate. colour by itself is a random variable, could contain anything. fido.colour or self.colour is like a form field on the Dog's identity sheet; and __init__ is the clerk filling it out for the first time.
Any clearer?
EDI...
Add up a column of numbers at the Unix shell
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. . .| x=$(echo <(cat)); echo $((0+${x// /+}+0)) if you want all bash all the time:
– qneill
Apr 3 '15 at 23:31
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Prototypical inheritance - writing up [duplicate]
...rototype.
Another reason could be that to create a Hamster a lot of complicated calculations need be done on passed arguments that may be not available yet, again you could pass in dummy arguments but it could unnecessarily complicate your code.
Extending and overriding Parent functions
Sometimes...
Assign output of os.system to a variable and prevent it from being displayed on the screen [duplicat
...ich I asked a long time ago, what you may want to use is popen:
os.popen('cat /etc/services').read()
From the docs for Python 3.6,
This is implemented using subprocess.Popen; see that class’s
documentation for more powerful ways to manage and communicate with
subprocesses.
Here's t...
Regular expression to match a word or its prefix
...ed the match or not. If you don't, better use the non-capture group to allocate more memory for calculation instead of storing something you will never need to use.
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