How to extract the number after specific word using awk? - linux

Question

I have several lines of text. I want to extract the number after specific word using awk.
I tried the following code but it does not work.
At first, create the test file by: vi test.text. There are 3 columns (the 3 fields are generated by some other pipeline commands using awk).
Index AllocTres CPUTotal
1 cpu=1,mem=256G 18
2 cpu=2,mem=1024M 16
3 4
4 cpu=12,gres/gpu=3 12
5 8
6 9
7 cpu=13,gres/gpu=4,gres/gpu:ret6000=2 20
8 mem=12G,gres/gpu=3,gres/gpu:1080ti=1 21
Please note there are several empty fields in this file.
what I want to achieve is to extract the number after the first gres/gpu= in each line (if no gres/gpu= occurs in this line, the default number is 0) using a pipeline like: cat test.text | awk '{some_commands}' to output 4 columns:
Index AllocTres CPUTotal GPUAllocated
1 cpu=1,mem=256G 18 0
2 cpu=2,mem=1024M 16 0
3 4 0
4 cpu=12,gres/gpu=3 12 3
5 8 0
6 9 0
7 cpu=13,gres/gpu=4,gres/gpu:ret6000=2 20 4
8 mem=12G,gres/gpu=3,gres/gpu:1080ti=1 21 3

Answer 1

Firstly: awk do not need cat, it could read files on its' own. Combining cat and awk is generally discouraged as useless use of cat.
For this task I would use GNU AWK following way, let file.txt content be
cpu=1,mem=256G
cpu=2,mem=1024M
cpu=12,gres/gpu=3
cpu=13,gres/gpu=4,gres/gpu:ret6000=2
mem=12G,gres/gpu=3,gres/gpu:1080ti=1
then
awk 'BEGIN{FS="gres/gpu="}{print $2+0}' file.txt
output
0
0
0
3
0
0
4
3
Explanation: I inform GNU AWK that field separator (FS) is gres/gpu= then for each line I do print 2nd field increased by zero. For lines without gres/gpu= $2 is empty string, when used in arithmetic context this is same as zero so zero plus zero gives zero. For lines with at least one gres/gpu= increasing by zero provokes GNU AWK to find longest prefix which is legal number, thus 3 (4th line) becomes 3, 4, (7th line) becomes 4, 3, (8th line) becomes 3.
(tested in GNU Awk 5.0.1)

Answer 2

With your shown samples in GNU awk you can try following code. Written and tested in GNU awk. Simple explanation would be using awk's match function where using regex gres\/gpu=([0-9]+)(escaping / here) and creating one and only capturing group to capture all digits coming after =. Once match is found printing current line followed by array's arr's 1st element +0(to print zero in case no match found for any line) here.
awk '
FNR==1{
print $0,"GPUAllocated"
next
}
{
match($0,/gres\/gpu=([0-9]+)/,arr)
print $0,arr[1]+0
}
' Input_file

Answer 3

Using sed
$ sed '1s/$/\tGPUAllocated/;s~.*gres/gpu=\([0-9]\).*~& \t\1~;1!{\~gres/gpu=[0-9]~!s/$/ \t0/}' input_file
Index AllocTres CPUTotal GPUAllocated
1 cpu=1,mem=256G 18 0
2 cpu=2,mem=1024M 16 0
3 4 0
4 cpu=12,gres/gpu=3 12 3
5 8 0
6 9 0
7 cpu=13,gres/gpu=4,gres/gpu:ret6000=2 20 4
8 mem=12G,gres/gpu=3,gres/gpu:1080ti=1 21 3

Answer 4

awk '
BEGIN{FS="\t"}
NR==1{
$(NF+1)="GPUAllocated"
}
NR>1{
$(NF+1)=FS 0
}
/gres\/gpu=/{
split($0, a, "=")
gp=a[3]; gsub(/[ ,].*/, "", gp)
$NF=FS gp
}1' test.text
Index AllocTres CPUTotal GPUAllocated
1 cpu=1,mem=256G 18 0
2 cpu=2,mem=1024M 16 0
3 4 0
4 cpu=12,gres/gpu=3 12 3
5 8 0
6 9 0
7 cpu=13,gres/gpu=4,gres/gpu:ret6000=2 20 4
8 mem=12G,gres/gpu=3,gres/gpu:1080ti=1 21 3