Bash to ksh problem

Shell Programming and Scripting
1

Hi all

Below code works in bash but it is not working in ksh.

enddate=`date -d "$enddate + $i day" "+%Y_%m_%d"`

Please help me how it works in ksh

Thanks

2

Replace shebang #!/bin/bash to #!/bin/ksh -xv (set xtrace & verbose) and run the code to reveal lines that are not KSH compliant.

For example, I see you are using string search and replace which I guess is not supported in KSH.

startdate="${1//_/-}"  # change underscores into dashes

Use sed instead to perform search and replace.

3

ksh does support it. But only ksh93 versions.

@OP: Which ksh version are you using? Are you running this on some machine not having GNU date installed?

4

I'd also replace the "echo"s with "print"s. "print" is a built-in command in ksh, while "echo" isn't.

What is equally ugly in ksh and in bash is this:

while [ 1 ]

It will work, but will use "test" to do so. Instead

while :

will do the same with less resources used.

I hope this helps.

bakunin

5

@Bakunin, can you site a version of ksh where echo is not builtin?

I have 11/16/88, 12/28/93 and mksh 41 and it appears to be builtin in all of these.

6

It might be built in but this is not required by the standard. The standard output command in ksh is "print" and if you use "echo" the shell executes "/bin/echo" if it is not built in. In the AIX ksh (a ksh88) this used to be so, but to be honest i haven't checked that lately.

bakunin

1 Like
7

Thanks, that might explain why a lot of the old AIX ksh scripts we have around here use print (I've always replaced them with echo or printf, whenever making updates - just because it's more portable).

8

I changed

#!/bin/bash

to

 #!/bin/ksh -xv

and
I got the error called

startdate="${1//_/-}"

:Bad substitution

Please help me

9

That is exactly what I said in my post before.

You have 2 options here:

  1. Use ksh93 like elixir_sinari suggested
#!/bin/ksh93
  1. Use sed like I suggested
startdate=$( echo $1 | sed 's/_/-/g' )
10

-d is not working in ksh.

enddate=`date -d "$enddate + $i day" "+%Y_%m_%d"`

If i remove -d from the above line igot the error called bad conversion

11

elixir_sinari already mentioned in his post that if you do not have GNU date then you will not be able to use -d option and perform date arithmetic.

I recommend you to take a look at this thread for alternatives.