[SOLVED] awk

freeroute · 09-15-2017, 10:59 AM

My file awk_test.txt contains:

Quote:

fred'eva'steve'
tom'java'mark
eve mark john

I would like to say to awk: the delimiter is "'" (not the default "space")

My command was:

Code:

awk 'BEGIN {FS ="'"} {print $1, $2}' awk_test.txt

Got a promt:

Code:

Why did not work?

This is working (field separator in this case is "space":

Code:

awk 'BEGIN {FS =" "} {print $1, $2}' awk_test.txt

fred'eva'steve'
tom'java'mark
eve mark

Could you help, please?

Turbocapitalist · 09-15-2017, 11:22 AM

There might be several ways. One is to let the shell handle the escape:

Code:

awk 'BEGIN{ FS="['\'' ]"; OFS="\t"; } { print $1, $2, $3; }'

Note carefully what is inside and outside of which kinds of quotes there. The \' ends up being processed by the shell and not by awk.

pan64 · 09-15-2017, 12:05 PM

probably:

Code:

awk -F"'" '{print $1, $2}' awk_test.txt

freeroute · 09-15-2017, 12:09 PM

Okay. It works. Thank you very much for your answer.

I know that in the character range I must use escape character at some special character: -, ^, }, ].
I tried to use only escape like:

Quote:

awk 'BEGIN{ FS="[\' ]"; OFS="\t"; } { print $1, $2, $3; }' awk_test.txt

. but it was not enough.
So why must use

Quote:

awk 'BEGIN{ FS="['\'' ]"; OFS="\t"; } { print $1, $2, $3; }' awk_test.txt

?

freeroute · 09-15-2017, 12:16 PM

Quote:

Originally Posted by pan64

probably:

Code:

awk -F"'" '{print $1, $2}' awk_test.txt

Thanks, it is also working.

pan64 · 09-15-2017, 12:20 PM

remember, between ' ': 'protected text' the protected text will not be evaluated by the shell, and it must not contain ', because that is the delimiter itself ( = beginning and the end)
Therefore you need to do the following:

Code:

awk                  # the command itself
'BEGIN{ FS="['       # first protected string
\'                   # a single '
' ]"; OFS="\t"; } { print $1, $2, $3; }'  # second protected string
filename

Turbocapitalist · 09-15-2017, 12:49 PM

Yes, anything between two single quotes is protected and won't be processed. It will be taken literally instead:

Code:

$ a='\"'
$ echo $a
\"

$ a="\""
$ echo $a
"

In the first example the backslash remains literally a backslash.

In the second example it is processed.

freeroute · 09-15-2017, 01:27 PM

Okay. Now I understand

Thank you.