unix - count of columns in file

Given a file with data like this (i.e. stores.dat file)

sid|storeNo|latitude|longitude
2|1|-28.03720000|153.42921670
9|2|-33.85090000|151.03274200

What would be a command to output the number of column names?

i.e. In the example above it would be 4. (number of pipe characters + 1 in the first line)

I was thinking something like:

awk '{ FS = "|" } ; { print NF}' stores.dat

but it returns all lines instead of just the first and for the first line it returns 1 instead of 4

awk -F'|' '{print NF; exit}' stores.dat 

Just quit right after the first line.

This is a workaround (for me: I don't use awk very often):

Display the first row of the file containing the data, replace all pipes with newlines and then count the lines:

$ head -1 stores.dat | tr '|' '\n' | wc -l

Unless you're using spaces in there, you should be able to use | wc -w on the first line.

wc is "Word Count", which simply counts the words in the input file. If you send only one line, it'll tell you the amount of columns.

You could try

>cat FILE | awk '{print NF}'

Perl solution similar to Mat's awk solution:

perl -F'\|' -lane 'print $#F+1; exit' stores.dat

I've tested this on a file with 1000000 columns.

---

If the field separator is whitespace (one or more spaces or tabs) instead of a pipe:

perl -lane 'print $#F+1; exit' stores.dat

If you have python installed you could try:

python -c 'import sys;f=open(sys.argv[1]);print len(f.readline().split("|"))' \
    stores.dat

This is usually what I use for counting the number of fields:

head -n 1 file.name | awk -F'|' '{print NF; exit}'

select any row in the file (in the example below, it's the 2nd row) and count the number of columns, where the delimiter is a space:

sed -n 2p text_file.dat | tr ' ' '\n' | wc -l

Based on Cat Kerr response. This command is working on solaris

awk '{print NF; exit}' stores.dat

you may try:

head -1 stores.dat | grep -o \|  | wc -l

Proper pure [tag:bash] way

Under bash, you could simply:

IFS=\| read -ra headline <stores.dat
echo ${#headline[@]}
4

A lot quicker as without forks, and reusable as $headline hold the full head line. You could, for sample:

printf " - %s\n" "${headline[@]}"
 - sid
 - storeNo
 - latitude
 - longitude

Nota This syntax will drive correctly spaces and others characters in column names.

Alternative: strong binary checking for max columns on each rows

What if some row do contain some extra columns?

This command will search for bigger line, counting separators:

tr -dc $'\n|' <stores.dat |wc -L
3

There are max 3 separators, then 4 fields.