Indent like first line

Question

How can I indent a file such as its first line?

Example:

A file containing

 x=1+2+3+4+ 5+6+7+8 +9+10+12

should be converted to

 x=1+2+3+4+ 5+6+7+8 +9+10+12

I need this inside a shell-script on a Linux system. One-liners are preferred.

are you limited to shell or can you use a scripting language? — amphibient
– amphibient, Commented Dec 13, 2012 at 16:53
@foampile I can use any common script language. Speed is less important. — jofel
– jofel, Commented Dec 13, 2012 at 17:03
i was gonna suggest Perl. @Birei below posted a good answer. albeit i am increasingly liking awk as well — amphibient
– amphibient, Commented Dec 13, 2012 at 17:07

Birei · Accepted Answer · 2012-12-13 16:47:01Z

One way using perl:

perl -pe 'if ($. == 1) { m/^(\s*)/; $space = $1 || q{}; next } s/^\s*/$space/' infile

It yields:

 x=1+2+3+4+ 5+6+7+8 +9+10+12

Kevin · Accepted Answer · 2012-12-13 16:55:30Z

5

You can do this in awk:

awk 'NR==1{split($0,a,/[^ \t]/)}{sub(/^[ \t]*/,a[1]);print}' file.in

answered Dec 13, 2012 at 16:55

41.7k17 gold badges91 silver badges113 bronze badges

Stéphane Chazelas · Accepted Answer · 2012-12-13 19:59:51Z

2

With sed:

sed -e '1{h;s/[^[:blank:]].*//;x;b' -e '}' -e 'G;s/[[:blank:]]*\(.*\)\n\(.*\)/\2\1/'

answered Dec 13, 2012 at 19:59

586k96 gold badges1.1k silver badges1.7k bronze badges

3 Answers 3