Shell Programming and Scripting

x 10
y 20
z 15

x 100
z  245

y 78
z 23

x 100
y 900
z 300

x 10    100    0    100
y 20    0       78   900
z 15    245    23   300

$ awk 'BEGIN{while (getline < "file1"){ map[$1]=$2 }}{x=map[$1];if ($1 in map){map[$1]=x" "$2}}END{for (i in map){print i,map[i]}}'  file2 file3 file4

x 10 100 100
y 20 78 900
z 15 245 23 300

awk 'BEGIN{while (getline < "file1"){ map[$1]=$2 }}{if (FNR == 1 && NR > 1){for (i in map){y=map[i];mn=split(y,m," ");if (mn < ln){map[i]=y " " 0;}}};x=map[$1];if ($1 in map){map[$1]=x " " $2;ln=split(map[$1],n," ");}}END{for (i in map){print i,map[i]}}' file2 file3 file4

x 10 100 0 100
y 20 0 78 900
z 15 245 23 300

$ awk 'FNR==1{++a}
        {A[$1,a]=$2;B[$1]++}
        END{for(i in B){
        for(j=1;j<=a;j++){
        t=A[i,j]?A[i,j]:"0"; s=s?s"\t"t:i"\t"t} print s; s="" }}
        ' file1 file2 file3 file4

x       10      100     0       100
y       20      0       78      900
z       15      245     23      300