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cr0c
Asked: 2014-08-14 23:50:58 +0800 CST

Bash convert character in variable

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I am writing a collectd nagios custom check script in bash. The problem I am having is that nagios shows hostnames as host.name.domain but collectd holds WSP files as host_name_domain. My question is how can I make a variable convert the hostname that it gets from nagios (host.name.domain) to collectd format (host_name_domain).

This is the part where the convertion has to occur. So the WSP_PATH would give out collectd format of hostname in variable $NHOST

WSP_PATH=/var/lib/carbon/whisper/ctd/$NHOST/uptime/uptime.wsp
bash

2 Answers

  1. Bash has the required functionality built in (unless it's an ancient version):

    WSP_PATH=/var/lib/carbon/whisper/ctd/${NHOST//./-}/uptime/uptime.wsp
    • 13
  2. Best Answer

    Use sed:

    $ NHOST="host.domain.tld"
$ NHOST=$(echo $NHOST | sed 's/\./-/g')
$ WSP_PATH=/var/lib/carbon/whisper/ctd/$NHOST/uptime/uptime.wsp
$ echo $WSP_PATH
/var/lib/carbin/whisper/ctd/host-domain/uptime/uptime.wsp

    As above, /g is required so that all instances of . are replaced with -

    Although on second thoughts, it would probably make more sense to perform this (sed) operation on the $NHOST variable (now edited to show this)

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