Linux – How to split a string against a character in BASH

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I would like to be able to split an authorization code by the - character so that I can operate on each segment individually. I do not want to use external binaries (awk, grep) – this is to be as minimalistic as possible. What are some ways I can achieve this?

Here is an example auth code:

82a8-bd7d-986d-9dc9-41f5-fc02-2c20-3175-097a-c1eb

Best Answer

Try using the Internal Field Separator (IFS):

AUTH_CODE='82a8-bd7d-986d-9dc9-41f5-fc02-2c20-3175-097a-c1eb'

OIFS=$IFS                   # store old IFS in buffer
IFS='-'                     # set IFS to '-'

for i in ${AUTH_CODE[@]}    # traverse through elements
do
  echo $i
done

IFS=$OIFS                   # reset IFS to default (whitespace)

Output:

82a8
bd7d
986d
9dc9
41f5
fc02
2c20
3175
097a
c1eb

By setting the Internal Field Separator, you split AUTH_CODE on the - character, allowing you to traverse through the newly-created elements in a foreach loop.

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Bash Scripting – How to Determine if a Bash Variable is Empty

This will return true if a variable is unset or set to the empty string ("").

if [ -z "${VAR}" ];

Bash – Create ‘Virtual File’ from Command Output

This is the cleanest way to do what you want:

mutt admin@example.org -a <(mysqldump mysqldumpoptions)

The <() operator is what you were asking for; it creates a FIFO (or /dev/fd) and forks a process and connects stdout to the FIFO. >() does the same, except connects stdin to the FIFO instead. In other words, it does all the mknod stuff for you behind the scenes; or on a modern OS, does it in an even better way.

Except, of course, that doesn't work with mutt, it says:

/dev/fd/63: unable to attach file.

I suspect the problem is that mutt is trying to seek in the file, which you can't do on a pipe of any sort. The seeking is probably something like scanning the file to figure out what MIME type it is and what encodings might work (ie, whether the file is 7bit or 8bit), and then seeking to the beginning of the file to actually encode it into the message.

If what you want to send is plain text, you could always do something like this to make it the main contents of the email instead (not ideal, but it actually works):

mysqldump mysqldumpoptions | mutt -s "Here's that mysqldump" admin@example.org

Best Answer

Related Solutions

Bash Scripting – How to Determine if a Bash Variable is Empty

Bash – Create ‘Virtual File’ from Command Output

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