I'm trying to reverse the order of words excluding first word in final output. For example, I have a word db.in.com.example I'm using this command to reverse the order
$ basename db.in.com.example | awk -F'.' '{ for (i=NF; i>1; i--) \
printf("%s.",$i); print $1; }'
example.com.in.db
I want to exclude last .db in the output. Like this
example.com.in
I'm having trouble with this. Can this be done using only awk ? Can anybody help me on this ?
$ echo db.in.com.example | awk -F. '{ # set . as delimiter
for(i=NF;i>1;i--) # loop from last to next-to-first
printf "%s%s", $i, (i==2?ORS:".") # output item and ORS or . after next-to-first
}'
example.com.in
If perl is okay
$ echo 'db.in.com.example' | perl -F'\.' -lane 'print join ".", reverse(#F[1..$#F])'
example.com.in
$ echo '1.2.3.db.in.com.example' | perl -F'\.' -lane 'print join ".", reverse(#F[2..$#F])'
example.com.in.db.3
-F'\.' set . as input field separator and save to #F array
reverse(#F[1..$#F]) will give reversed array of elements from index 1 to last index
similarly, #F[2..$#F] will exclude first and second element
join "." to add . as separator between elements of array
See http://perldoc.perl.org/perlrun.html#Command-Switches for details on command line options
You can use cut, tac, and parameter expansion:
reverse=$(basename db.in.com.example |
cut -d. -f2- --output-delimiter=$'\n' |
tac )
echo ${reverse//$'\n'/.}
You've got some nice answers here. I am adding one which in my opinion is more readable, of course if ruby is an option for you:
$ echo "db.in.com.example" | ruby -ne 'p ($_.strip.split(".").drop(1).reverse.join("."))'
"example.com.in"
try following too once, which will reverse the text and it allows you to remove any string from output not only db, you need to just change the variable's value and it should fly then.
echo "db.in.com.example" | awk -v var="db" -F"." '{for(i=NF;i>0;i--){val=$i!=var?(val?val FS $i:$i):val};print val;val=""}'
EDIT: Adding a non-one liner form of solution too now.
echo "db.in.com.example" | awk -v var="db" -F"." '{
for(i=NF;i>0;i--){
val=$i!=var?(val?val FS $i:$i):val
}
print val;val=""
}'
I am trying to pass a for loop index i into awk but keep getting unexpected token awk errors.
First I tried using the -v option within awk:
for i in "${myarray}"
awk -v var=$i '/var/{print}' myfile.dat
done
I also tried calling the variable directly using single quotes:
for i in "${myarray}"
awk '/'"$i"'/{print}' myfile.dat
done
My end goal is to learn how to pass a for loop index variable through awk as the search pattern. I'd like the above code to search through myfile.dat and print lines which contain the strings in myarray.
There are 2 problems:
Array traversing should be like this for i in "${myarray[#]}"
awk treats text between /.../ as regex literal, to use a variable use $0 ~ var.
Your code should be:
for i in "${myarray[#]}"; do
awk -v var="$i" '$0 ~ var' myfile.dat
done
{print} is default action in awk that you can omit as shown above.
you can do the same loop free as well, e.g.,
echo "${myarray[#]}" | tr ' ' '|' | awk 'NR==FNR{pat=$0; next} $0 ~ pat' - file
Given this line:
12,34,56,47,56,34,56,78,90,12,12,34,45
If the count of the commas(,) is greater than four, replace 4th comma(,) with ||.
If the count is lesser or equal to 4 no need replace the comma(,).
I am able to find the count by the following awk:
awk -F\, '{print NF-1}' text.txt
then I used an if condition to check if the result is greater than 4. But unable to replace 4th comma with ||
Find the count of the delimiter in a line and replace the particular position with another character.
Update:
I want to replace comma with || symbol after every 4th occurrence of the comma. Sorry for the confusion.
Expected output:
12,34,56,47||56,34,56,78||90,12,12,34||45
With GNU awk for gensub():
$ echo '12,34,56,47,56,34' | awk -F, 'NF>5{$0=gensub(/,/,"||",4)}1'
12,34,56,47||56,34
$ echo '12,34,56,47,56' | awk -F, 'NF>5{$0=gensub(/,/,"||",4)}1'
12,34,56,47,56
$ echo 12,34,56,47,56,34,56,78,90,12,12,34,45 | sed 's/,/||/4'
12,34,56,47||56,34,56,78,90,12,12,34,45
$ echo 12,34,56,47 | sed 's/,/||/4'
12,34,56,47
Should work with any POSIX sed
Update:
For the updated question you can use
$ echo 12,34,56,47,56,34,56,78,90,12,12,34,45 | sed -e 's/\(\([^,]*,\)\{3\}[^,]*\),/\1||/g'
12,34,56,47||56,34,56,78||90,12,12,34||45
Unfortunately, POSIX sed's s command can take either a number or g as a flag, but not both. GNU sed allows the combination, but it does not do what we want in this case. So you have to spell it out in the regular expression.
Using awk you can do:
s='12,34,56,47,56,34,56,78,90,12,12,34,45'
awk -F, '{for (i=1; i<NF; i++) printf "%s%s", $i, (i%4?FS:"||"); print $i}' <<< "$s"
12,34,56,47||56,34,56,78||90,12,12,34||45
if the count is greater than four i want to replace 4th comma(,) with
||
give this line a try (gnu sed):
sed -r '/([^,]*,){4}.*,/s/,/||/4' file
test:
kent$ echo ",,,,,"|sed -r '/([^,]*,){4}.*,/s/,/||/4'
,,,||,
kent$ echo ",,,,"|sed -r '/([^,]*,){4}.*,/s/,/||/4'
,,,,
kent$ echo ",,,"|sed -r '/([^,]*,){4}.*,/s/,/||/4'
,,,
with awk
awk -F, 'NF-1>4{for(i=1;i<NF;i++){if(i==4)k=k$i"||";else k=k$i","} print k$NF}' filename
I have a simple bash script which is getting the load average using uptime and awk, for example
LOAD_5M=$(uptime | awk -F'load averages:' '{ print $2}' | awk '{print $2}')
However this includes a ',' at the end of the load average
e.g.
0.51,
So I have then replaced the comma with a string replace like so:
LOAD_5M=${LOAD_5M/,/}
I'm not an awk or bash wizzkid so while this gives me the result I want, I am wondering if there is a succinct way of writing this, either by:
Using awk to get the load average without the comma, or
Stripping the comma in a single line
You can do that in same awk command:
uptime | awk -F 'load averages?: *' '{split($2, a, ",? "); print a[2]}'
1.32
The 5 min load is available in /proc/loadavg. You can simply use cut:
cut -d' ' -f2 /proc/loadavg
With awk you can issue:
awk '{print $2}' /proc/loadavg
If you are not working on Linux the file /proc/loadavg will not being present. In this case I would suggest to use sed, like this:
uptime | sed 's/.*, \(.*\),.*,.*/\1/'
uptime | awk -F'load average:' '{ print $2}' | awk -F, '{print $2}'
0.38
(My uptime output has 'load average:' singular)
The load average numbers are always the last 3 fields in the 'uptime' output so:
IFS=' ,' read -a uptime_fields <<<"$(uptime)"
LOAD_5M=${uptime_fields[#]: -2:1}