Some useful variables and settings in the Korn Shell

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

Here are some hidden "gems" ...

• -C sets "noclobber" mode in which redirects do not overwrite files

$ set -C

$ 

$ ls > fred

$ ls > fred

ksh: cannot create fred: File exists

$ set +C

$ ls > fred

$

• CDPATH lets you change the target for your cd command to a list of directories whihc are searched in turn.

$ CDPATH=/etc:/bin

$ pwd

/home/trainee/sefas/f

$ cd

$ pwd

/home/trainee

$ cd init.d

/etc/init.d

$



• OLDPWD remembers where you were last in ksh, and cd - takes you there



$ pwd

/home/trainee

$ echo $OLDPWD

/etc/init.d

$ cd -

/etc/init.d

$ 



• Korn Shell - elapsed seconds, and a randon number between 0 and 32767



$ echo $SECONDS

14294

$ r

echo $SECONDS

14297

$ r

echo $SECONDS

14299

$ r

echo $SECONDS

14301

$ echo $RANDOM

28369

$ r

echo $RANDOM

5877

$ r

echo $RANDOM

28995

$  
(written 2008-05-30)


 Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
A172 - Web Application Deployment - Korn Shell - interactive and programming facilities
  [1361] Korn shell course - (2007-09-22)
  [1364] Korn shell course - resources - (2007-09-24)
  [1365] Korn Shell scripts on the web - (2007-09-25)
  [1367] korn tips - some useful korn shell techniques - (2007-09-25)
  [1659] String, Integer, Array, Associative Array - ksh variables - (2008-05-30)
  [1660] Korn shell - some nuggets - (2008-05-30)




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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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