CODEWITHSUNDEEP
bashtr
Krimson
Krimson

Reputation: 7674

Using tr to replace non-alpha characters with '-' is adding an extra character to end of string

I have the following string hello/world I want to replace the / with - to get hello-world

I've tried the following: http://rextester.com/NMIOL63413

$ echo hello/world | tr -c '[:alnum:]' '-'
$ hello-world-

Why is there an extra - at the end and how to I get rid of it?

Upvotes: 2

Views: 2243

Answers (1)

Inian
Inian

Reputation: 85800

It should be obvious that echo prints a \n at the end of each string. Since with the -c, you are looking to replace characters which are not part of [:alnum:]. Since the new-line is also not part of a valid alphanumeric character, it also gets substituted.

In such situations where you are unsure which "magical" character is present or gets substituted, do a hexdump to see within the string. You could see the \n at the end.

echo hello/world | hexdump -c
0000000   h   e   l   l   o   /   w   o   r   l   d  \n
000000c

So to avoid such instances of new-line and other shell meta-characters messing with your replacement string, always use printf:

printf '%s' 'hello/world' | tr -c '[:alnum:]' '-'

Upvotes: 7

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