ken@images1.Waterloo.NCR.COM (Ken Braithwaite) (09/28/90)
I am trying to peel off one at a time the letters from a variable
in the Bourne shell, ie from Bourne get B and ourne.
How can I do this?
Thanks in advance.
----------------------------------------------------------------------
Ken Braithwaite | They couldn't hit an elephant at
| this dist
These opinions are solely | last words, General Sedgwick
my own. I don't share. |
----------------------------------------------------------------------lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (09/29/90)
In article <1308@ncrwat.Waterloo.NCR.COM> ken@images1.Waterloo.NCR.COM (Ken Braithwaite) writes:
: I am trying to peel off one at a time the letters from a variable
: in the Bourne shell, ie from Bourne get B and ourne.
: How can I do this?
A fairly efficient way would be
echo "Bourne" | SOMETHING | while read line; do
...
done
where SOMETHING is one of
sed 's/\(.\)/\1\
/g
s/\n$//'
perl -pe 'chop; s/./$&\n/g'
There are lots of other ways.
Larry Wall
lwall@jpl-devvax.jpl.nasa.govmerlyn@iwarp.intel.com (Randal Schwartz) (09/30/90)
In article <9737@jpl-devvax.JPL.NASA.GOV>, lwall@jpl-devvax (Larry Wall) writes: | perl -pe 'chop; s/./$&\n/g' | | There are lots of other ways. Ack. Just to even out the "do everything in Perl" reputation I've gotten, here's how to do it *without* Perl. (And I'm even doing this as a followup to Larry's article... sheesh. If that doesn't even out the score, I don't know what will!) a="Bourne" # pretend you already have it in $a first=`expr "$a" : '\(.\).*'` # to get the first char a=`expr "$a" : '.\(.*\)` # to trim the first char off echo "$first $a" [no whitespace in $a, please] or even: a="Bourne" # pretend you already have it in $a eval `echo "$a" | sed 's/\(.\)\(.*\)/first=\1 a="\2"/'` echo "$first $a" [This requires well-behaved values of $a... whitespace is OK, quoting characters are out.] There. Not a single 'perl' invocation in the pile :-) Just another Bourne-shell hacker, -- /=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\ | on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III | | merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn | \=Cute Quote: "Welcome to Portland, Oregon, home of the California Raisins!"=/
pim@cti-software.nl (Pim Zandbergen) (09/30/90)
How about
string=`echo $string | cut -c1`
I don't think the Bourne shell can do this without executing
an external command.
In Korn shell you can use a hack like
string=${string%${string#?}}
--
Pim Zandbergen domain : pim@cti-software.nl
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2585 GD The Hague, The Netherlands fax : +31 70 3512837mark@hsi.UUCP (Mark Sicignano) (09/30/90)
In article <9737@jpl-devvax.JPL.NASA.GOV>, lwall@jpl-devvax (Larry Wall) writes: > perl -pe 'chop; s/./$&\n/g' > > There are lots of other ways. > In article <1990Sep29.193617.25752@iwarp.intel.com> merlyn@iwarp.intel.com (Randal Schwartz) writes: > >a="Bourne" # pretend you already have it in $a >first=`expr "$a" : '\(.\).*'` # to get the first char >a=`expr "$a" : '.\(.*\)` # to trim the first char off >echo "$first $a" > >[no whitespace in $a, please] > >or even: > >a="Bourne" # pretend you already have it in $a >eval `echo "$a" | sed 's/\(.\)\(.*\)/first=\1 a="\2"/'` >echo "$first $a" > Double ack! These ways might work, but what about readability! echo "Bourne" | awk ' { for (i = 0; i < length; i++) { print substr($0, i + 1, 1); } }' Produces: B o u r n e That's what you want, right? -mark -- Mark Sicignano ...!uunet!hsi!mark 3M Health Information Systems mark@hsi.com --
scott@tab00.larc.nasa.gov (Scott Yelich) (10/01/90)
>I don't think the Bourne shell can do this without executing >an external command. Uh, it CAN be done... the question is whether you want to fork another process or have a massive hack to accomplish something which is actually a minimal function (Lets pass a lisp function to get the first letter to emacs... etc). As an EXAMPLE only, and an example which YOU can expand... STRING="STRING" set +F case "$STRING" in S* ) FIRST=S;; esac echo "The first letter of \`\`$STRING'' is \`\`$FIRST\'\' Now, do you REALLY want to do this? -- Signature follows. [Skip now] ----------------------------------------------------------------------------- Scott D. Yelich scott@[xanth.]cs.odu.edu [128.82.8.1] After he pushed me off the cliff, he asked me, as I fell, ``Why'd you jump?'' Administrator of: Game-Design requests to <game-design-request@cs.odu.edu> ODU/UNIX/BSD/X/C/ROOT/XANTH/CS/VSVN/ -----------------------------------------------------------------------------
das@oahu.cs.ucla.edu (David Smallberg) (10/02/90)
In article <1990Sep29.215559.25098@cti-software.nl> pim@cti-software.nl (Pim Zandbergen) writes: >How about >In Korn shell you can use a hack like > >string=${string%${string#?}} A fixed-length variable also does the trick: typeset -L1 first="$string" rest=${string#$first} Unfortunately, a non- or not clearly documented feature of left- (right-) justified variables is that leading (trailing) whitespace is stripped off before the truncating assignment is made, so that string=" abc" typeset -L1 first="$string" echo ">$first<" yields >a< instead of > < -- -- David Smallberg, das@cs.ucla.edu, ...!{uunet,ucbvax,rutgers}!cs.ucla.edu!das
cevert@airgun.wg.waii.com (C C Evert) (10/02/90)
In article <1308@ncrwat.Waterloo.NCR.COM>, ken@images1.Waterloo.NCR.COM (Ken Braithwaite) writes: > I am trying to peel off one at a time the letters from a variable > in the Bourne shell, ie from Bourne get B and ourne. > How can I do this? > Thanks in advance. > expr "$SHELL" : '\(.\).*' prints the first letter of SHELL expr "$SHELL" : '.\(.*\)' prints all but the first letter of SHELL You still need to check for SHELL being empty. -- C C Evert Western Geophysical - A division of Western Atlas International, A Litton/Dresser Company DOMAIN addr: cevert@airgun.wg.waii.com UUNET address: uunet!airgun!cevert
les@chinet.chi.il.us (Leslie Mikesell) (10/02/90)
In article <1990Sep29.215559.25098@cti-software.nl> pim@cti-software.nl (Pim Zandbergen) writes: >How about >string=`echo $string | cut -c1` >I don't think the Bourne shell can do this without executing >an external command. There's always something like: string=foo for i in a b c d e f g (you know the rest...) do case "$string" in $i*) first=$i break ;; esac done echo $first Les Mikesell les@chinet.chi.il.us