config file, get field.

Shell Programming and Scripting
1

Hi Everyone,
I have a txt file: a.txt

a_b_ 3
c_d_e_ 55

(Assume this a.txt got 100 lines, here i just list 2 lines)
How should i get the 2nd field when 1st field eq c_d_e_. my way is:

`cat a.txt | grep c_d_e_ | cut -f2 -d' '`

Is there simple way, more efficient way in regular expression, perl? awk? and etc. :confused:
Thanks

2

Are you saying the fields are split on spaces?

If so, it's trivial with awk or Perl and even with just bash:

while read line
do
set $line
echo $2
done
3

better (don't use cat with grep !)

grep c_d_e_ a.txt | cut f2 -d' '
4

Examples of awk and sed would be

$(awk '/c_d_e_/{print $2}' a.txt)

or

$(sed -n 's/^c_d_e_ *//p' a.txt)
5

Thanks Scrutinizer, frans, Tony.

6

to be even more specific since you are checking field 1

awk '$1=="c_d_e_"{print $2}' file