awk - replacing stings in file1 with column1 in file2

Shell Programming and Scripting
1

Hello,

I've never used awk before, but from what I've read, it will best suit what I'm trying to do. I have 2 files. I need to replace strings in file1 with the first column of a matching string in file2. Below are examples:

File1:
random-string1
1112
1232
3213
2131
random-string2
1231
1112
3213

File2:
DD 3213
CCA 1231
AABC 1112
ADFDFF 1232
DDFSCC 2131

Output File3:
random-string1
AABC
ADFDFF
DD
DDFSCC
random-string2
CCA
AABC
DD

I tried something like:
grep `cat file1` file2 | awk {'print $1'} > file3

I lose the random-strings with my output. I'm sure there's an easier way to do it with awk alone and drop the grep.

Thanks

2

try this

awk 'FILENAME=="file2"{A[$2]=$1}
FILENAME=="file1"{if(A[$1]){print A[$1]}else{print $0}}' file2 file1
3

Thank you for the quick reply. I apologize if this is a novice question, but so I'm clear, I would run it like this?

file1=master.txt
file2=ref.txt

awk 'FILENAME=="ref.txt"{A[$2]=$1}
FILENAME=="master.txt"{if(A[$1]){print A[$1]}else{print $0}}' ref.txt master.txt

When I try that, I have no output - I'm sure I'm not using it correctly.

Thanks

4

you are doing it correctly..
you are not getting any errors right??
and are you sure that file contents are same as you given in your question.. i mean no special character and all.

5

I see where I went wrong.. my examples were not accurate. My apologies.

in file2 (ref.txt) the values look more like this:

File2:
DD 3213
CCA 1231
AA BC 1112
ADFDFF 1232
DDF SCC 2131

I ran this:

awk 'FILENAME=="ref.txt"{A[$2]=$1}
FILENAME=="master.txt"{if(A[$1]){print A[$1]}else{print $0}}' ref.txt master.txt > output.txt

Any string in file 2 that had spaces (AA BC, DDF SCC) did not work for obvious reasons. I've regenerated file 2 to look like this now with sed:

DD:3213
CCA:1231
AA BC:1112
ADFDFF:1232
DDF SCC:2131

Is there any way I can use the awk script you gave me to recognize the columns separated by the colon? I can change the colon to any other value as well if there is something that will work better with awk.

Thanks for the help and patience.

---------- Post updated at 01:39 AM ---------- Previous update was at 01:18 AM ----------

I tried this but no lucK:

awk 'FILENAME=="ref.txt"{FS = : ; A[$2]=$1}
FILENAME=="master.txt"{if(A[$1]){print A[$1]}else{print $0}}' ref.txt master.txt > results.txt

awk: FILENAME=="ref.txt"{FS = : ; A[$2]=$1}
awk: ^ syntax error

---------- Post updated at 01:53 AM ---------- Previous update was at 01:39 AM ----------

Thank you for the help vidyadhar85.

I was able to get it to work with this:

awk '
BEGIN{FS=":"}
FILENAME=="ref.txt"{A[$2]=$1}
FILENAME=="master.txt"{if(A[$1]){print A[$1]}else{print $0}}' ref.txt master.txt > results.txt
6

even this will do..

awk 'FILENAME=="file2"{FS=":";A[$2]=$1}
FILENAME=="file1"{if(A[$1]){print A[$1]}else{print $0}}' file2 file1
7

I'm not sure if I should create a new thread or not - I'm seeing now that before I run the awk script, I need to adjust File1.

Again:
File1:
random-string1
1112
1232
3213
2131
random-string2
1231
1112
3213

I need to insert some text in front of each of the random-strings. The random strings always begin with letters. Looking for output:

File1:
PAGE-random-string1
1112
1232
3213
2131
PAGE-random-string2
1231
1112
3213

Thanks

8

small change..

awk 'FILENAME=="file2"{FS=":";A[$2]=$1}
FILENAME=="file1"{if(A[$1]){print A[$1]}else{print "PAGE-"$0}' file2 file1