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Transaction isolation levels relation with locks on table
I have read about 4 levels of isolation:
3 Answers
3
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How to get a password from a shell script without echoing
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Here is another way to do it:
#!/bin/bash
# Read Password
echo -n Password:
read -s password
echo
# Run Command
echo $password
The read -s will turn off echo for you. Just replace the echo on the last line with the command you want to run.
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Why use a READ UNCOMMITTED isolation level?
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This isolation level allows dirty reads. One transaction may see uncommitted changes made by some other transaction.
To maintain the highest level of isolation, a DBMS usually acquires locks on data, which may result in a loss of concurrency and a high locki...
How to read from a file or STDIN in Bash?
The following Perl script ( my.pl ) can read from either the file on the command line args or from STDIN:
15 Answers
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Read user input inside a loop
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Read from the controlling terminal device:
read input </dev/tty
more info: http://compgroups.net/comp.unix.shell/Fixing-stdin-inside-a-redirected-loop
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How do you read from stdin?
...o do it.
sys.stdin is a file-like object on which you can call functions read or readlines if you want to read everything or you want to read everything and split it by newline automatically. (You need to import sys for this to work.)
If you want to prompt the user for input, you can use raw_input...
Only read selected columns
Can anyone please tell me how to read only the first 6 months (7 columns) for each year of the data below, for example by using read.table() ?
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Read a file line by line assigning the value to a variable
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The following reads a file passed as an argument line by line:
while IFS= read -r line; do
echo "Text read from file: $line"
done < my_filename.txt
This is the standard form for reading lines from a file in a loop. Explanation:
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Is it safe to parse a /proc/ file?
...ommit that made it atomic. On a pre-2.6.30 kernel, you can open the file, read a bit of it, then if you later come back and read again, the piece you get will be inconsistent with the first piece. (I just demonstrated this -- try it yourself for fun.)
/proc/mounts is atomic within a single read sys...
Confused by python file mode “w+”
... a with statement like you should be. Then you'd do something like this to read from your file:
with open('somefile.txt', 'w+') as f:
# Note that f has now been truncated to 0 bytes, so you'll only
# be able to read data that you write after this point
f.write('somedata\n')
f.seek(0...