How to print columns one after the other in bash? - bash

Question

Is there any better methods to print two or more columns into one column, for example
input.file
AAA 111
BBB 222
CCC 333
output:
AAA
BBB
CCC
111
222
333
I can only think of:
cut -f1 input.file >output.file;cut -f2 input.file >>output.file
But it's not good if there are many columns, or when I want to pipe the output to other commands like sort.
Any other suggestions? Thank you very much!

Answer 1

With awk
awk '{if(maxc<NF)maxc=NF;
for(i=1;i<=NF;i++){(a[i]!=""?a[i]=a[i]RS$i:a[i]=$i)}
}
END{
for(i=1;i<=maxc;i++)print a[i]
}' input.file

Answer 2

You can use a GNU awk array of arrays to store all the data and print it later on.
If the number of columns is constant, this works for any amount of columns:
gawk '{for (i=1; i<=NF; i++) # loop over columns
data[i][NR]=$i # store in data[column][line]
}
END {for (i=1;i<=NR;i++) # loop over lines
for (j=1;j<=NF;j++) # loop over columns
print data[i][j] # print the given field
}' file
Note NR stands for number of records (that is, number of lines here) and NF stands for number of fields (that is, the number of fields in a given line).
If the number of columns changes over rows, then we should use yet another array, in this case to store the number of columns for each row. But in the question I don't see a request for this, so I am leaving it for now.
See a sample with three columns:
$ cat a
AAA 111 123
BBB 222 234
CCC 333 345
$ gawk '{for (i=1; i<=NF; i++) data[i][NR]=$i} END {for (i=1;i<=NR;i++) for (j=1;j<=NF;j++) print data[i][j]}' a
AAA
BBB
CCC
111
222
333
123
234
345
If the number of columns is not constant, using an array to store the number of columns for each row helps to keep track of it:
$ cat sc.wk
{for (i=1; i<=NF; i++)
data[i][NR]=$i
columns[NR]=NF
}
END {for (i=1;i<=NR;i++)
for (j=1;j<=NF;j++)
print (i<=columns[j] ? data[i][j] : "-")
}
$ cat a
AAA 111 123
BBB 222
CCC 333 345
$ awk -f sc.wk a
AAA
BBB
CCC
111
222
333
123
-
345

Answer 3

awk '{print $1;list[i++]=$2}END{for(j=0;j<i;j++){print list[j];}}' input.file
Output
AAA
BBB
CCC
111
222
333
More simple solution would be
awk -v RS="[[:blank:]\t\n]+" '1' input.file

Answer 4

Expects tab as delimiter:
$ cat <(cut -f 1 asd) <(cut -f 2 asd)
AAA
BBB
CCC
111
222
333

Answer 5

Since the order is of no importance:
$ awk 'BEGIN {RS="[ \t\n]+"} 1' file
AAA
111
BBB
222
CCC
333

Answer 6

Ugly, but it works-
for i in {1..2} ; do awk -v p="$i" '{print $p}' input.file ; done
Change the {1..2} to {1..n} where 'n' is the number of columns in the input file
Explanation-
We're defining a variable p which itself is the variable i. i varies from 1 to n and at each step we print the 'i'th column of the file.

Answer 7

This will work for an arbitrary number fo space separated colums
awk '{for (A=1;A<=NF;A++) printf("%s\n",$A);}' input.file | sort -u > output.file
If space is not the separateor ... let's suppose ":" is the separator
awk -F: '{for (A=1;A<=NF;A++) printf("%s\n",$A);}' input.file | sort -u > output.file