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Shell Programming and Scripting

understand sed

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# 1  
Old 06-02-2015
understand sed
Code:
cat teledir.txt
jai sharma 25853670
chanchal singhvi 9831545629
anil aggarwal 9830263298
shyam saksena 23217847
lalit chowdury 26688726

If i use the below command , it is giving me the output with "," in between two name. how ? and also i would like to know the reason for the space used in between ([a-z]*\) *\([a-z]*\) and \2, \1/' and what is the use of specifying two [a-z] and what *\ means?

Code:
sed 's/\([a-z]*\) *\([a-z]*\)/\2, \1/' teledir.txt | sort

aggarwal, anil 9830263298
chowdury, lalit 26688726
saksena, shyam 23217847
sharma, jai 25853670
singhvi, chanchal 9831545629

Last edited by joeyg; 06-02-2015 at 02:50 PM.. Reason: Please wrap scripts/commands and data inside CodeTags
# 2  
Old 06-02-2015
Quote:
Originally Posted by ANTONY ANKROSE
.
.
.
If i use the below command , it is giving me the output with "," in between two name. how ?
Because you told it to with \2, \1 (the "replacement" string)

Quote:
and also i would like to know the reason for the space used in between ([a-z]*\) *\([a-z]*\)
to separate given from family name
Quote:
and \2, \1/'
to swap and separate family from given name
Quote:
and what is the use of specifying two [a-z]
one for given, one for family name
Quote:
and what *\ means?
Nothing. * is the repeater/multiplier for the preceding "atom" (character(s)), \ escapes the char to follow.

May I advise reading man sed and man regex?
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