[clug] Bash questions...

steve jenkin sjenkin at canb.auug.org.au
Sat Apr 30 19:39:06 MDT 2011

Yesterday I wanted a short bash construct to write a line of dashes to
separate blocks of output, ie:

blah blah blah
yaddah yaddah yaddah
and so on

But without doing my usual, v. simple:
 echo "--------------------------------------------------" :-)

The bash on my Mac is not-quite-recent, so I can't use 'seq', but the
older form:
 for i in {1..10};do ....;done

 steve$ bash --version
GNU bash, version 3.2.48(1)-release (x86_64-apple-darwin10.0)

Attempt 1:
 steve$ for i in {1..20};do echo -n "-";done;echo

Attempt 2:
 steve$ yes -|head -20|tr -d '\n';echo

steve$ yes ''|head -20|tr '\n' '-';echo

 steve$ printf "%s\n" $(yes ''|head -20|tr '\n' '-')

I thought of using 'dd if=/dev/zero bs=1 count=20', but that's a bit long...

=> Someone out there is CLUG land is going to have a great little recipe
for this and related tasks...

Perhaps something with the shell variable pattern matching, or the
string 'expr'??

A recursive function, if it doesn't blow up the stack, could be very short.

Preloading a variable with a very long string, then somehow pulling out
a substring could also work. [There's "array variable BASH_REMATCH"]

python/perl/sed one-liners are also welcome :-)

And "for extra credit", any new interesting thing you've been doing :=]

Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin

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