Shell Programming and Scripting

123
456
789
111
222
333
444
555

...    789    yyy    xxx    zzz    11111
...    111    xxx    yyy    aaa    22222
...    222    zzz    xxx    yyy    33333

awk -F'\t' 'NR==FNR{A[$1]=$2; next} $2 in A{$3=A[$3] $3 in A{$4=A[$4]}}1' file1 file2 > output
awk: cmd. line:1: NR==FNR{A[$1]=$2; next} $2 in A{$3=A[$3] $3 in A{$4=A[$4]}}1
awk: cmd. line:1:

...    789    yyy    xxx
...    111    xxx    yyy
...    222    zzz    xxx

123
456
...    789    yyy    xxx
...    111    xxx    yyy
...    222    zzz    xxx
333
444
555

awk 'NR == FNR {T[$2] = $1 FS $2 FS $3 FS $4; next} $1 in T {$1 = T[$1]} 1' FS="\t" file2 file1
123
456
...	789	yyy	xxx
...	111	xxx	yyy
...	222	zzz	xxx
333
444
555

awk '
BEGIN {	FS = OFS = "\t"
}
NR == 1 {
	outfile = FILENAME
}
FNR == NR {
	o[i[++ic] = $1] = $1
}
{	if($2 in o)
		o[$2] = $1 OFS $2 OFS $3 OFS $4
}
END {	for(j = 1; j <= ic; j++)
		print o[i[j]] > outfile
}' file1 file2

123     1     2
456     a     b
456     x     y
789     x     y

456     x     y     z     1
789     x     y     z     2

awk '
BEGIN {FS = OFS = "\t"
}
NR == 1 {
outfile = FILENAME
}
FNR == NR {
o[i[++ic] = $1,$2,$3] =$1        
}
{if($2 in o)
o[$2] = $1 OFS $2 OFS $3 OFS $4
}
END {for(j = 1; j <= ic; j++)
print o[i[j]] > outfile
}' file1 file2

123     1     2
456     a     b
456     x     y     z
789     x     y     z

123
456
789
111
222
333
444
555