bash array question

[Joseph Sinclair]

Try using an anchored expression and doing a double-swap to handle the double-ended case:
################################################################################
#!/bin/bash
Unix=('Debian' 'Red Hat' 'HP' 'My HP' 'SCO Unix' 'Suse' 'Fedora' 'UTS' 'OpenLinux'
'HP-UX' 'HP');

echo ${Unix[@]/SCO Unix/Ubuntu}
# quoting is important here, else tokens with embedded spaces turn into multiple tokens!
tmpArray=( "${Unix[@]/%HP/THIS_IS_A_FALSE_TOKEN}" )
tmpArray=( "${tmpArray[@]/#THIS_IS_A_FALSE_TOKEN}" )
tmpArray=( "${tmpArray[@]/%THIS_IS_A_FALSE_TOKEN/HP}" )
Unix=("${tmpArray[@]}")

echo ${Unix[@]}
################################################################################

On 06/20/2011 11:35 AM, Nathan England wrote:
> I use a lot of arrays in bash, but I have never before needed to modify the
> contents of the array once I had created it, but now I need to. I followed
> the tutorial on this page:
> http://www.thegeekstuff.com/2010/06/bash-array-tutorial/
> 
> and it gives an example of
> 
> #########################
> $cat arraymanip.sh
> #!/bin/bash
> Unix=('Debian' 'Red hat' 'Ubuntu' 'Suse' 'Fedora' 'UTS' 'OpenLinux'
> 'HP-UX');
> 
> echo ${Unix[@]/Ubuntu/SCO Unix}
> 
> $./arraymanip.sh
> Debian Red hat SCO Unix Suse Fedora UTS OpenLinux
> ##################################
> 
> So I decided to try creating a new array and replacing what I don't want
> with nothing by doing the following:
> 
> tmpArray=( ${Unix[@]/deleteme/} )
> Unix=("${tmpArray[@]}")
> 
> So far this has worked great, but I've run into a problem. Say I have 'HP'
> and 'HP-UX' in my array and I want to remove the 'HP', so I would do
> tmpArray=( ${Unix[@]/HP/} )
> Unix=("${tmpArray[@]}")
> 
> at first glance this worked fine, until I realized that now, instead of
> 'HP-UX' in my array, I now have '-UX'
> It seems to replace all instances, which is what I want, but the pattern
> matches even in this example, which is what I don't want.
> 
> Following his tutorial, I would need to know the number of the element in
> the array I want to delete, but my problem is there may be 10 instances in
> the array of 'HP' and I want to delete them all, so I would need to loop
> through it over and over until all instances are gone. Also, the elements
> inserted into the array are variables and I don't necessarily know the order
> of the elements, so I cannot just tell it to delete element X like in his
> example. The array is not static anywhere in my script.
> 
> So how do I remove something from an array without having to run through
> every element in an array and test for whole matches? My array might be 100
> elements large, which can take a LONG time to loop through when I am adding
> or removing another hundred items to the array. I liked this pattern replace
> because it was fast, I don't want to lose my speed now!
> 
> Thanks for your help.
> 
> 
> 
> 
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