awk - concatenate two string variable and assign to a third - awk

In awk, I have 2 fields: $1 and $2.
They are both strings that I want to concatenate and assign to a variable.


Just use var = var1 var2 and it will automatically concatenate the vars var1 and var2:
awk '{new_var=$1$2; print new_var}' file
You can put an space in between with:
awk '{new_var=$1" "$2; print new_var}' file
Which in fact is the same as using FS, because it defaults to the space:
awk '{new_var=$1 FS $2; print new_var}' file
Test
$ cat file
hello how are you
i am fine
$ awk '{new_var=$1$2; print new_var}' file
hellohow
iam
$ awk '{new_var=$1 FS $2; print new_var}' file
hello how
i am
You can play around with it in ideone: http://ideone.com/4u2Aip


Could use sprintf to accomplish this:
awk '{str = sprintf("%s %s", $1, $2)} END {print str}' file


You can also concatenate strings from across multiple lines with whitespaces.
$ cat file.txt
apple 10
oranges 22
grapes 7
Example 1:
awk '{aggr=aggr " " $2} END {print aggr}' file.txt
10 22 7
Example 2:
awk '{aggr=aggr ", " $1 ":" $2} END {print aggr}' file.txt
, apple:10, oranges:22, grapes:7


Concatenating strings in awk can be accomplished by the print command AWK manual page, and you can do complicated combination. Here I was trying to change the 16 char to A and used string concatenation:
echo CTCTCTGAAATCACTGAGCAGGAGAAAGATT | awk -v w=15 -v BA=A '{OFS=""; print substr($0, 1, w), BA, substr($0,w+2)}'
Output: CTCTCTGAAATCACTAAGCAGGAGAAAGATT
I used the substr function to extract a portion of the input (STDIN). I passed some external parameters (here I am using hard-coded values) that are usually shell variable. In the context of shell programming, you can write -v w=$width -v BA=$my_charval. The key is the OFS which stands for Output Field Separate in awk. Print function take a list of values and write them to the STDOUT and glue them with the OFS. This is analogous to the perl join function.
It looks that in awk, string can be concatenated by printing variable next to each other:
echo xxx | awk -v a="aaa" -v b="bbb" '{ print a b $1 "string literal"}'
# will produce: aaabbbxxxstring literal

Related

gawk - Delimit lines with custom character and no similar ending character

Let's say I have a file like so:
test.txt
one
two
three
I'd like to get the following output: one|two|three
And am currently using this command: gawk -v ORS='|' '{ print $0 }' test.txt
Which gives: one|two|three|
How can I print it so that the last | isn't there?

Here's one way to do it:
$ seq 1 | awk -v ORS= 'NR>1{print "|"} 1; END{print "\n"}'
1
$ seq 3 | awk -v ORS= 'NR>1{print "|"} 1; END{print "\n"}'
1|2|3
With paste:
$ seq 1 | paste -sd'|'
1
$ seq 3 | paste -sd'|'
1|2|3

Convert one column to one row with field separator:
awk '{$1=$1} 1' FS='\n' OFS='|' RS='' file
Or in another notation:
awk -v FS='\n' -v OFS='|' -v RS='' '{$1=$1} 1' file
Output:
one|two|three
See: 8 Powerful Awk Built-in Variables – FS, OFS, RS, ORS, NR, NF, FILENAME, FNR

awk solutions work great. Here is tr + sed solution:
tr '\n' '|' < file | sed 's/\|$//'
1|2|3

just flatten it :
gawk/mawk 'BEGIN { FS = ORS; RS = "^[\n]*$"; OFS = "|"
} NF && ( $NF ? NF=NF : —-NF )'
ascii | = octal \174 = hex 0x7C. The reason for —-NF is that more often than not, the input includes a trailing new line, which makes field count 1 too many and result in
1|2|3|
Both NF=NF and --NF are similar concepts to $1=$1. Empty inputs, regardless of whether trailing new lines exist or not, would result in nothing printed.
At the OFS spot, you can delimit it with any string combo you like instead of being constrained by tr, which has inconsistent behavior. For instance :
gtr '\012' '高' # UTF8 高 = \351\253\230 = xE9 xAB x98
on bsd-tr, \n will get replaced by the unicode properly 1高2高3高 , but if you're on gnu-tr, it would only keep the leading byte of the unicode, and result in
1 \351 2 \351 . . .
For unicode equiv-classes, bsd-tr works as expected while gtr '[=高=]' '\v' results in
gtr: ?\230: equivalence class operand must be a single character
and if u attempt equiv-classes with an arbitrary non-ASCII byte, bsd-tr does nothing while gnu-tr would gladly oblige, even if it means slicing straight through UTF8-compliant characters :
g3bn 77138 | (g)tr '[=\224=]' '\v'
bsd-tr : 77138=Koyote 코요태 KYT✜ 高耀太
gnu-tr : 77138=Koyote ?
?
태 KYT✜ 高耀太

I would do it following way, using GNU AWK, let test.txt content be
one
two
three
then
awk '{printf NR==1?"%s":"|%s", $0}' test.txt
output
one|two|three
Explanation: If it is first line print that line content sans trailing newline, otherwise | followed by line content sans trailing newline. Note that I assumed that test.txt has not trailing newline, if this is not case test this solution before applying it.
(tested in gawk 5.0.1)

Also you can try this with awk:
awk '{ORS = (NR%3 ? "|" : RS)} 1' file
one|two|three
% is the modulo operator and NR%3 ? "|" : RS is a ternary expression.
See Ed Morton's explanation here: https://stackoverflow.com/a/55998710/14259465

With a GNU sed, you can pass -z option to match line breaks, and thus all you need is replace each newline but the last one at the end of string:
sed -z 's/\n\(.\)/|\1/g' test.txt
perl -0pe 's/\n(?!\z)/|/g' test.txt
perl -pe 's/\n/|/g if !eof' test.txt
See the online demo.
Details:
s - substitution command
\n\(.\) - an LF char followed with any one char captured into Group 1 (so \n at the end of string won't get matched)
|\1 - a | char and the captured char
g - all occurrences.
The first perl command matches any LF char (\n) not at the end of string ((?!\z)) after slurping the whole file into a single string input (again, to make \n visible to the regex engine).
The second perl command replaces an LF char at the end of each line except the one at the end of file (eof).
To make the changes inline add -i option (mind this is a GNU sed example):
sed -i -z 's/\n\(.\)/|\1/g' test.txt
perl -i -0pe 's/\n(?!\z)/|/g' test.txt
perl -i -pe 's/\n/|/g if !eof' test.txt

AWK Match & Split not finding string pattern

Passing the following commands I would expect the first to split the string (which is also a regex) into two array elements and the second command (match) to print [[:blank:]].
echo "new[[:blank:]]+File\(" | awk '{ split($0, a, "[[:blank:]]"); print a[1]}'
prints the whole string as it has not split
echo "new[[:blank:]]+File\(" | awk '{ match($0, /[[:blank:]]/, m)}END{print m[0]}'
prints nothing
What am I missing here?
UPDATE
I'm calling an awk script with the following command;
awk -v regex1=new[[:blank:]]+File\( -f parameterisedRegexAwkScript.awk "$file" >> "output.txt"
Then in the my script I attempt to split on the string literal with the following command;
len = split(regex1, regex, /[[:blank:]]/, seps
but when I print len it's value is 1 when I would have expected it to be 2

echo "new[[:blank:]]+File\(" | awk '{ split($0, a, "[[:blank:]]"); print a[1]}'
3rd argument for split works like setting FS in BEGIN, so in this case you instruct to split at any whitespace, you need to escape [ and ]. Let file.txt content be
new[[:blank:]]+File\(
then
awk '{split($0, a, "\\[\\[:blank:\\]\\]"); print a[1]}' file.txt
output
new
(tested in gawk 4.2.1)

linux csv file concatenate columns into one column

I've been looking to do this with sed, awk, or cut. I am willing to use any other command-line program that I can pipe data through.
I have a large set of data that is comma delimited. The rows have between 14 and 20 columns. I need to recursively concatenate column 10 with column 11 per row such that every row has exactly 14 columns. In other words, this:
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p
will become:
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p
I can get the first 10 columns. I can get the last N columns. I can concatenate columns. I cannot think of how to do it in one line so I can pass a stream of endless data through it and end up with exactly 14 columns per row.
Examples (by request):
How many columns are in the row?
sed 's/[^,]//g' | wc -c
Get the first 10 columns:
cut -d, -f1-10
Get the last 4 columns:
rev | cut -d, -f1-4 | rev
Concatenate columns 10 and 11, showing columns 1-10 after that:
awk -F',' ' NF { print $1","$2","$3","$4","$5","$6","$7","$8","$9","$10$11}'

Awk solution:
awk 'BEGIN{ FS=OFS="," }
{
diff = NF - 14;
for (i=1; i <= NF; i++)
printf "%s%s", $i, (diff > 1 && i >= 10 && i < (10+diff)?
"": (i == NF? ORS : ","))
}' file
The output:
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p

With GNU awk for the 3rd arg to match() and gensub():
$ cat tst.awk
BEGIN{ FS="," }
match($0,"(([^,]+,){9})(([^,]+,){"NF-14"})(.*)",a) {
$0 = a[1] gensub(/,/,"","g",a[3]) a[5]
}
{ print }
$ awk -f tst.awk file
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p

If perl is okay - can be used just like awk for stream processing
$ cat ip.txt
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p
1,2,3,4,5,6,3,4,2,4,3,4,3,2,5,2,3,4
1,2,3,4,5,6,3,4,2,4,a,s,f,e,3,4,3,2,5,2,3,4
$ awk -F, '{print NF}' ip.txt
16
18
22
$ perl -F, -lane '$n = $#F - 4;
print join ",", (#F[0..8], join("", #F[9..$n]), #F[$n+1..$#F])
' ip.txt
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p
1,2,3,4,5,6,3,4,2,43432,5,2,3,4
1,2,3,4,5,6,3,4,2,4asfe3432,5,2,3,4
-F, -lane split on , results saved in #F array
$n = $#F - 4 magic number, to ensure output ends with 14 columns. $#F gives the index of last element of array (won't work if input line has less than 14 columns)
join helps to stitch array elements together with specified string
#F[0..8] array slice with first 9 elements
#F[9..$n] and #F[$n+1..$#F] the other slices as needed
Borrowing from Ed Morton's regex based solution
$ perl -F, -lape '$n=$#F-13; s/^([^,]*,){9}\K([^,]*,){$n}/$&=~tr|,||dr/e' ip.txt
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p
1,2,3,4,5,6,3,4,2,43432,5,2,3,4
1,2,3,4,5,6,3,4,2,4asfe3432,5,2,3,4
$n=$#F-13 magic number
^([^,]*,){9}\K first 9 fields
([^,]*,){$n} fields to change
$&=~tr|,||dr use tr to delete the commas
e this modifier allows use of Perl code in replacement section
this solution also has the added advantage of working even if input field is less than 14

You can try this gnu sed
sed -E '
s/,/\n/9g
:A
s/([^\n]*\n)(.*)(\n)(([^\n]*\n){4})/\1\2\4/
tA
s/\n/,/g
' infile

First variant - with awk
awk -F, '
{
for(i = 1; i <= NF; i++) {
OFS = (i > 9 && i < NF - 4) ? "" : ","
if(i == NF) OFS = "\n"
printf "%s%s", $i, OFS
}
}' input.txt
Second variant - with sed
sed -r 's/,/#/10g; :l; s/#(.*)((#[^#]){4})/\1\2/; tl; s/#/,/g' input.txt
or, more straightforwardly (without loop) and probably faster.
sed -r 's/,(.),(.),(.),(.)$/#\1#\2#\3#\4/; s/,//10g; s/#/,/g' input.txt
Testing
Input
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u
Output
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p
a,b,c,d,e,f,g,h,i,jklmn,o,p,q,r
a,b,c,d,e,f,g,h,i,jklmnopq,r,s,t,u

Solved a similar problem using csvtool. Source file, copied from one of the other answers:
$ cat input.txt
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p
1,2,3,4,5,6,3,4,2,4,3,4,3,2,5,2,3,4
1,2,3,4,5,6,3,4,2,4,a,s,f,e,3,4,3,2,5,2,3,4
Concatenating columns:
$ cat input.txt | csvtool format '%1,%2,%3,%4,%5,%6,%7,%8,%9,%10%11%12,%13,%14,%15,%16,%17,%18,%19,%20,%21,%22\n' -
a,b,c,d,e,f,g,h,i,jkl,m,n,o,p,,,,,,
1,2,3,4,5,6,3,4,2,434,3,2,5,2,3,4,,,,
1,2,3,4,5,6,3,4,2,4as,f,e,3,4,3,2,5,2,3,4
anatoly#anatoly-workstation:cbs$ cat input.txt

gawk FS to split record into individual characters

If the field separator is the empty string, each character becomes a separate field
$ echo hello | awk -F '' -v OFS=, '{$1 = NF OFS $1} 1'
5,h,e,l,l,o
However, if FS is a regex that can possibly match zero times, the same behaviour does not occur:
$ echo hello | awk -F ' *' -v OFS=, '{$1 = NF OFS $1} 1'
1,hello
Anyone know why that is? I could not find anything in the gawk manual. Is FS="" just a special case?
I'm most interested in understanding why the 2nd case does not split the record into more fields. It's as if awk is treating FS=" *" like FS=" +"

Interesting question!
I just pulled gnu-awk 4.1.0's codes, I think the answer we could find in the file field.c.
line 371:
* re_parse_field --- parse fields using a regexp.
*
* This is called both from get_field() and from do_split()
* via (*parse_field)(). This variation is for when FS is a regular
* expression -- either user-defined or because RS=="" and FS==" "
*/
static long
re_parse_field(lo...
also this line: (line 425):
if (REEND(rp, scan) == RESTART(rp, scan)) { /* null match */
here is the case of <space>* matching in your question. The implementation didn't increment the nf, that is, it thinks the whole line is one single field. Note this function was used in do_split() function too.
First, if FS is null string, gawk separates each char into its own field. gawk's doc has clearly written this, also in codes, we could see:
line 613:
* null_parse_field --- each character is a separate field
*
* This is called both from get_field() and from do_split()
* via (*parse_field)(). This variation is for when FS is the null string.
*/
static long
null_parse_field(long up_to,
If the FS has single character, awk won't consider it as regex. This was mentioned in doc too. Also in codes:
#line 667
* sc_parse_field --- single character field separator
*
* This is called both from get_field() and from do_split()
* via (*parse_field)(). This variation is for when FS is a single character
* other than space.
*/
static long
sc_parse_field(l
if we read the function, no regex match handling was done there.
In the comments of the function re_parse_field(), and sc_parse_field(), we see do_split invokes them too. It explains why we have 1 in following command instead of 3:
kent$ echo "foo"|awk '{split($0,a,/ */);print length(a)}'
1
Note, to avoid to make the post too long, I didn't paste the complete codes here, we can find the codes here:
http://git.savannah.gnu.org/cgit/gawk.git/

As was mentioned, an empty field separator generates undefined behavior; the same code will give different results on different platforms / flavors of awk. For example (all Mac OSX 10.8.5):
> echo hello | awk -F '' -v OFS=, '{$1 = NF OFS $1} 1'
awk: field separator FS is empty
1,hello
So awk complains, but keeps going.
Let's look at some other examples:
> echo hello | awk -F '.' -v OFS=, '{$1 = NF OFS $1} 1'
1,hello
A . by itself is not considered a regular expression
> echo hello | awk -F '[.]' -v OFS=, '{$1 = NF OFS $1} 1'
1,hello
Still nothing
> echo hello | awk -F '.?' -v OFS=, '{$1 = NF OFS $1} 1'
6,,,,,,
Now we have something like a regex: .? is "zero or one character". It is expanded to one character (which is consumed), so the output is "a whole lot of nothings"
> echo hello | awk -F '*' -v OFS=, '{$1 = NF OFS $1} 1'
1,hello
Not a regular expression
> echo hello | awk -F '.*' -v OFS=, '{$1 = NF OFS $1} 1'
2,,
A regular expression that consumes the entire thing
> echo hello | awk -F 'l' -v OFS=, '{$1 = NF OFS $1} 1'
3,he,,o
Match the letter l twice - two empty strings
> echo hello | awk -F 'ell' -v OFS=, '{$1 = NF OFS $1} 1'
2,h,o
Match all of ell at once
> echo hello | awk -F '.?|' -v OFS=, '{$1 = NF OFS $1} 1'
awk: illegal primary in regular expression .?| at
input record number 1, file
source line number 1
Attempt to be clever: sometimes an | with empty string on one side will match "anything" but awk's regex engine doesn't like it.
Conclusion - the regular expressions cannot match "empty", and whatever is matched is consumed. Attempts to use (?:.) or even (?=.) generate errors.

It seems to be a special case in gawk.
Traditionally, the behavior of FS equal to "" was not defined. In this
case, most versions of Unix awk simply treat the entire record as only
having one field. (d.c.) In compatibility mode (see Options), if FS is
the null string, then gawk also behaves this way.

What POSIX has to say about this:
If FS is a null string, the behavior is unspecified.
So the gawk behaviour is implementation-specific and sort of explains why your two examples don't yield the same output.

Another data point: gawk and perl disagree on how to do this:
$ perl -E '$,=","; $s="hello"; $r=qr( *); #s=split($r,$s); say scalar(#s), #s'
5,h,e,l,l,o
$ gawk 'BEGIN {s="hello";r=" *";n=split(s,a,r); print n,a[n]; if (s~r) print "match"}'
1 hello
match
$ gawk 'BEGIN {s="hello";r=""; n=split(s,a,r); print n,a[n]; if (s~r) print "match"}'
5 o
match

How to split a delimited string into an array in awk?

How to split the string when it contains pipe symbols | in it.
I want to split them to be in array.
I tried
echo "12:23:11" | awk '{split($0,a,":"); print a[3] a[2] a[1]}'
Which works fine. If my string is like "12|23|11" then how do I split them into an array?

Have you tried:
echo "12|23|11" | awk '{split($0,a,"|"); print a[3],a[2],a[1]}'

To split a string to an array in awk we use the function split():
awk '{split($0, array, ":")}'
# \/ \___/ \_/
# | | |
# string | delimiter
# |
# array to store the pieces
If no separator is given, it uses the FS, which defaults to the space:
$ awk '{split($0, array); print array[2]}' <<< "a:b c:d e"
c:d
We can give a separator, for example ::
$ awk '{split($0, array, ":"); print array[2]}' <<< "a:b c:d e"
b c
Which is equivalent to setting it through the FS:
$ awk -F: '{split($0, array); print array[2]}' <<< "a:b c:d e"
b c
In GNU Awk you can also provide the separator as a regexp:
$ awk '{split($0, array, ":*"); print array[2]}' <<< "a:::b c::d e
#note multiple :
b c
And even see what the delimiter was on every step by using its fourth parameter:
$ awk '{split($0, array, ":*", sep); print array[2]; print sep[1]}' <<< "a:::b c::d e"
b c
:::
Let's quote the man page of GNU awk:
split(string, array [, fieldsep [, seps ] ])
Divide string into pieces separated by fieldsep and store the pieces in array and the separator strings in the seps array. The first piece is stored in array[1], the second piece in array[2], and so forth. The string value of the third argument, fieldsep, is a regexp describing where to split string (much as FS can be a regexp describing where to split input records). If fieldsep is omitted, the value of FS is used. split() returns the number of elements created. seps is a gawk extension, with seps[i] being the separator string between array[i] and array[i+1]. If fieldsep is a single space, then any leading whitespace goes into seps[0] and any trailing whitespace goes into seps[n], where n is the return value of split() (i.e., the number of elements in array).

Please be more specific! What do you mean by "it doesn't work"?
Post the exact output (or error message), your OS and awk version:
% awk -F\| '{
for (i = 0; ++i <= NF;)
print i, $i
}' <<<'12|23|11'
1 12
2 23
3 11
Or, using split:
% awk '{
n = split($0, t, "|")
for (i = 0; ++i <= n;)
print i, t[i]
}' <<<'12|23|11'
1 12
2 23
3 11
Edit: on Solaris you'll need to use the POSIX awk (/usr/xpg4/bin/awk) in order to process 4000 fields correctly.

I do not like the echo "..." | awk ... solution as it calls unnecessary fork and execsystem calls.
I prefer a Dimitre's solution with a little twist
awk -F\| '{print $3 $2 $1}' <<<'12|23|11'
Or a bit shorter version:
awk -F\| '$0=$3 $2 $1' <<<'12|23|11'
In this case the output record put together which is a true condition, so it gets printed.
In this specific case the stdin redirection can be spared with setting an awk internal variable:
awk -v T='12|23|11' 'BEGIN{split(T,a,"|");print a[3] a[2] a[1]}'
I used ksh quite a while, but in bash this could be managed by internal string manipulation. In the first case the original string is split by internal terminator. In the second case it is assumed that the string always contains digit pairs separated by a one character separator.
T='12|23|11';echo -n ${T##*|};T=${T%|*};echo ${T#*|}${T%|*}
T='12|23|11';echo ${T:6}${T:3:2}${T:0:2}
The result in all cases is
112312

Actually awk has a feature called 'Input Field Separator Variable' link. This is how to use it. It's not really an array, but it uses the internal $ variables. For splitting a simple string it is easier.
echo "12|23|11" | awk 'BEGIN {FS="|";} { print $1, $2, $3 }'

I know this is kind of old question, but I thought maybe someone like my trick. Especially since this solution not limited to a specific number of items.
# Convert to an array
_ITEMS=($(echo "12|23|11" | tr '|' '\n'))
# Output array items
for _ITEM in "${_ITEMS[#]}"; do
echo "Item: ${_ITEM}"
done
The output will be:
Item: 12
Item: 23
Item: 11

Joke? :)
How about echo "12|23|11" | awk '{split($0,a,"|"); print a[3] a[2] a[1]}'
This is my output:
p2> echo "12|23|11" | awk '{split($0,a,"|"); print a[3] a[2] a[1]}'
112312
so I guess it's working after all..

echo "12|23|11" | awk '{split($0,a,"|"); print a[3] a[2] a[1]}'
should work.

echo "12|23|11" | awk '{split($0,a,"|"); print a[3] a[2] a[1]}'

code
awk -F"|" '{split($0,a); print a[1],a[2],a[3]}' <<< '12|23|11'
output
12 23 11

The challenge: parse and store split strings with spaces and insert them into variables.
Solution: best and simple choice for you would be convert the strings list into array and then parse it into variables with indexes. Here's an example how you can convert and access the array.
Example: parse disk space statistics on each line:
sudo df -k | awk 'NR>1' | while read -r line; do
#convert into array:
array=($line)
#variables:
filesystem="${array[0]}"
size="${array[1]}"
capacity="${array[4]}"
mountpoint="${array[5]}"
echo "filesystem:$filesystem|size:$size|capacity:$capacity|mountpoint:$mountpoint"
done
#output:
filesystem:/dev/dsk/c0t0d0s1|size:4000|usage:40%|mountpoint:/
filesystem:/dev/dsk/c0t0d0s2|size:5000|usage:50%|mountpoint:/usr
filesystem:/proc|size:0|usage:0%|mountpoint:/proc
filesystem:mnttab|size:0|usage:0%|mountpoint:/etc/mnttab
filesystem:fd|size:1000|usage:10%|mountpoint:/dev/fd
filesystem:swap|size:9000|usage:9%|mountpoint:/var/run
filesystem:swap|size:1500|usage:15%|mountpoint:/tmp
filesystem:/dev/dsk/c0t0d0s3|size:8000|usage:80%|mountpoint:/export

awk -F'['|'] -v '{print $1"\t"$2"\t"$3}' file <<<'12|23|11'