Bash - Sequence of numbers in the same line

Question

I know the command seq to generate sequence of integers, one per line, but I would like to ask two questions:

1. Is it possible to write the numbers of the sequence in the same line?

2. Is it possible to create a string made of the sequence of numbers separated by a white space?

Answer 1

With bash, zsh and ksh93, you can use {start..end..step} brace expansion form:

$ echo {1..10}
1 2 3 4 5 6 7 8 9 10

Answer 2

GNU seq takes separator (-s) option :

$ seq -s ' ' 1 5
1 2 3 4 5

$ var="$(seq -s ' ' 1 5)"
$ echo "$var"
1 2 3 4 5

Answer 3

Portable to all shells and any system that has seq (as this questions is tagged)

If start is 1:

$ echo $(seq 10)
1 2 3 4 5 6 7 8 9 10

Otherwise:

$ echo $(seq 5 10)
5 6 7 8 9 10

With bc:

$ echo $(echo "for (i=0;i<=1000;i++) i"| bc)

In bash

echo {1..10}

Note:

This echo solution works if the value of IFS contains a newline, which it does by default.
By default IFS is set to the sequence <space><tab><newline>. And is reset for each clean start of the shell. But, if you have any concern that it may have changed in some extreme corner case, we have several solutions.

Under bash, zsh, ksh just use: IFS=$' \t\n' (skip all the rest of this answer).

---

However, resetting the value of IFS under sh may be complex Read the complete detail here.

Unset IFS.

$ unset IFS; echo $(seq 5 10)                           #Always work.

will always work. Provided that there will be no code below (or child scripts) that need IFS set, such as a script which does OldIFS="$IFS".

Correct solution.

Using a trick for sh:

sh -c 'IFS="$(printf " \t\nx")"; IFS="${IFS%x}"; printf "$IFS"|xxd'  # correct.

Answer 4

Use this:

string="$(seq -s " " 1 10)"

Answer 5

seq 10 |xargs

...or...

seq 10 |paste -s -

Both of the commands above will separate the integers by whitespace. xargs defaults to imitating /bin/echo and so each integer is separated by a single space. It will default to a max command line length of 128K, though. You can adjust this...

seq 100000 | xargs -s2093009 | wc -l

...prints 1. I the value for-s here isn't arbitrary - I got it after trying a higher value (which apparently worked anyway) but afterward xargs printed the helpful message:

-s value should be <2093010

paste is one of two (to my knowledge) POSIX-sanctioned utilities for handling lines of arbitrary length:

paste specification application usage:

Most of the standard utilities work on text files. The cut utility can be used to turn files with arbitrary line lengths into a set of text files containing the same data. The paste utility can be used to create (or recreate) files with arbitrary line lengths.

text files

A file that contains characters organized into zero or more lines. The lines do not contain NUL characters and none can exceed {LINE_MAX} bytes in length, including the \newline character. Although POSIX.1-2008 does not distinguish between text files and binary files (see the ISO C standard), many utilities only produce predictable or meaningful output when operating on text files. The standard utilities that have such restrictions always specify text files in their STDIN or INPUT FILES sections.

paste defaults to a tab delimiter, and so there will be a tab between each integer following the second command. You can...

seq 10 |paste -sd ' ' - 

...use the -delimiter switch to alter that behavior,