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up vote 5 down vote favorite

How can I create a data file with one column in which there will be 1000 rows with zero values?

something like:

output:

0
0
0
0
0
.
.

.

share|improve this question
up vote 7 down vote accepted

Simply,

printf '0\n%.0s' {1..1000}

or using for loop,

for i in {1..1000}; do echo "0"; done

using awk,

awk 'BEGIN{for(c=0;c<1000;c++) print "0"}'

As @StéphaneChazelas pointed out, Using {1..1000} requires zsh or recent versions of bash, yash or ksh93 and also means storing the whole range in memory (possibly several times). You'll find it becomes a lot slower (if it doesn't crash for OOM) than using awk or yes 0 | head ... for large ranges like {1..10000000}. Or in other words it doesn't scale well. Possible workaround would be to use 

for ((i=0; i<=10000000;i++)); do echo 0; done

(ksh93/zsh/bash) wouldn't have the memory issue but would still be orders of magnitude slower than a dedicated tool or real programming language approach.

share|improve this answer
    
The printf command might fail when 1000 gets replaced with 1000000 because the shell would fail execve(2) with E2BIG – Basile Starynkevitch yesterday
1  
Using {1..1000} requires zsh or recent versions of bash, yash or ksh93 and also means storing the whole range in memory (possibly several times). You'll find it becomes a lot slower (if it doesn't crash for OOM) than using awk or yes|head for large ranges like {1..10000000}. Or in other words it doesn't scale well. – Stéphane Chazelas yesterday
    
@BasileStarynkevitch, the shells that support {x..y} (zsh, ksh93, bash and yash) all have printf builtin, so the E2BIG doesn't apply. – Stéphane Chazelas yesterday
    
@StéphaneChazelas I am completely agree with you. Is there any other workaround in this case ? – Rahul yesterday
1  
for ((i=0; i<=10000000;i++)); do echo 0; done (ksh93/zsh/bash) wouldn't have the memory issue but would still be orders of magnitude slower than a dedicated tool or real programming language approach. – Stéphane Chazelas yesterday
up vote 11 down vote

You might use yes(1) for that (piped into head(1)...):

yes 0 | head -n 1000 > data_file_with_a_thousand_0s.txt

and if you need a million zeros, replace the 1000 with 1000000

PS. In the old days, head -1000 was enough since equivalent to head -n 1000 today.

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1  
This definitely feels like "the Unix way" - glue some simple elements together into a pipe. It's worth noting though that the bare "-1000" argument is deprecated and the standard form (as listed on the man page you linked) is now "-n 1000". See e.g. unix.com/man-page/posix/1p/head and gnu.org/software/coreutils/manual/html_node/head-invocation for confirmation of this history. – IMSoP 21 hours ago
    
Brilliant. Didn't know yes existed. – Tulains Córdova 18 hours ago
up vote 6 down vote 
perl -e 'print "0\n" x 1000' > file.txt
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1  
I find it's by far the fastest for large numbers of rows (even than its python -c 'import sys; sys.stdout.write("0\n" * 1000)' equivalent or the yes|head approach). – Stéphane Chazelas yesterday
1  
However, it means storing the whole output in memory before printing it so also has scalability issues. – Stéphane Chazelas yesterday
up vote 2 down vote 
python2 -c 'print "0\n" * 1000' > file.txt
share|improve this answer
    
that will print an extra blank line, you would have to use trailing comma (,) at the end of command to prevent this. – Rahul yesterday
    
Agree. Thanks.. – Mrigesh yesterday
1  
This only works in the old python2, in Python 3 print no longer is a statement – Anthon yesterday
up vote -1 down vote

seq could be used: 

seq 0 0 0 | head -1000
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