Generator comprehensions return generator in single assignment variable, but in multiple assignment it doesn’t return generators.
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# generator comprehension gen = ((x for x in [1, 2, 3])) gen >><generator object <genexpr> at 0x7f92b4e33500> # returns not generator but each lists # if assign multiple variables lst1, lst2 = ((x for x in ([1, 2, 3],[4, 5, 6]))) lst1 >>[1, 2, 3] lst2 >>[4, 5, 6] |
Using List Comprehensions, we don’t have to write ‘lamda’ expressions to map or filter values and the code is simpler.
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dct_lst = [{'key1': 1, 'key2': 2}, {'key1': 2, 'key2': 3}] # using list comprehension result = [x['key2'] * 10 for x in dct_lst if x['key1'] == 1] print result # [20] # using map() and filter() result = map(lambda x: x['key2'] * 10, filter( lambda x: x['key1'] == 1, dct_list ) ) print result # [20] |
To check whether a process was restarted, look ‘/var/run/{process name}.pid’ file’s timestamp.
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# before % ll /var/run/apache2/apache2.pid -rw-r--r-- 1 root root 5 March 22 11:10 /var/run/apache2/apache2.pid # restart % sudo service apache2 restart * Restarting web server apache2 # the timestamp has updated % ll /var/run/apache2/apache2.pid -rw-r--r-- 1 root root 5 March 22 11:25 /var/run/apache2/apache2.pid |
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$ cat file aaa bbb\ccc bbb$ccc $ grep \\\\ file bbb\ccc $ grep '\\' file bbb\ccc $ grep \\$ file bbb$ccc $ grep '\$' file bbb$ccc |
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