To bash or not to bash

I have been inspired by Chen to talk about bash…

I have been using ksh for many years, and I mean ksh88 not ksh93. The main reason is, I want my script to run the same way in any Unix flavor.

ksh93 has never been too much popular. I used it a few time to sleep half a second


echo sleep 0.5| /usr/dt/bin/dtksh

ksh has a lot of nice features. I just used one of them in my script :


$ typeset -u name
$ read name?"Enter your name : "
Enter your name : Laurent
$ echo $name
LAURENT

Way easier to force a variable to be uppercase rather than using echo|tr etc

Bash has some nice features too, but unfortunately every OS release come with a different bash version, which is the same pain as perl when you want to write a script that last for a decade or two.

Ok, just4fun


$ mkdir -p {a..z}/{1..9}
... create directories a/1 a/2 ... z/8 z /9
$ [[ text =~ t..t ]] 
... check if text matches regular expression t..t
$ echo ${text/pattern/string}
... replace pattern by string

The first two commands require bash3, the last is just fine with bash2.

Have fun shell-scripting 🙂

8 Comments

  • ksh is way more artistic than bash. For example, in bash, if you want the time in your prompt, you do something like PS1=’\t ‘

    In ksh, I found this a few years ago, enjoy…

    
    export SECONDS="$(date '+3600*%H+60*%M+%S')"
    hh="(SECONDS/3600)%24"
    mm="(SECONDS/60)%60"
    ss="(SECONDS%60)"
    time='${_x[ (_m=mm)==(_h=hh)==(_s=ss) ]}$_h:$_m:$_s'
    PS1="($time) : "
    

  • Why should I flashback my database in 10g if my restore and recover scripts work very fine since release 8.0??
    🙂

    (the sum of Two+Eight is “Ten” or 10 ???)

  • not sure how it is related to bash but the key answer is time to recover!

    Since 8.0 your db has grown a lot, did you also update your tape libraries to maintain a reasonable time to recover? Maybe your HA requirements just changed in such a way a downtime of 1 hour got unacceptable, well, probably you do not need flashback database 🙂 (it is 10)

  • I was joking about features that comes with latest releases and scripts that last for a decade 😉
    Actually I write my scripts with latest features of bash,gawk, and perl (the perl shipped within oracle) for a certain platform because I guess future installations will do have at least these ones! I rearrange/rewrite indeed the scripts for various unix flavours.
    Could I live without JMX just because java 1.4 doesn’t have it? 😛

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