[mdlug] UNIX tips: Learn 10 good UNIX usage habits

[Aaron Kulkis]

Clinton V. Weiss wrote:
> Aaron Kulkis wrote:
>> Michael Corral wrote:
>>   
>>> 2008-03-10, Monsieur Robert Citek a ecrit:
>>>     
>>>> contrast the output of these commands:
>>>>
>>>> $ cat /etc/passwd /etc/group | grep root
>>>> $ grep root /etc/passwd /etc/group
>>>>       
>>> grep -h root /etc/passwd /etc/group
>>>
>>> That will give the same output as the cat+pipe version.
>>> So calling cat is unnecessary in this example, since the one grep
>>> command does the same as two commands and a pipe.
>>>
>>> In my experience I've found that calling cat is unnecessary about 95%
>>> of the time.
>>>
>>>     
>> The only times cat is necessary...
>>
>> 1: you want the to use one of the flags of cat, such as:
>>     cat -n file1 | cmd
>>     to prepend each line with a line number.
>>
>> 2: Multiple files to be processed as a single input stream.
>>
>>     cat file1 file2 [file3...] | cmd
> 
> 3. I want to quickly read the contents of the file.
> 
> Clinton =)

That would be true in 1983.
However, since then has come the invention
of both more....and less, too!

more file
or  cmd | more


less file
or  cmd | less]


(Less allows you to page backwards through piped input).