4

Running the following command:

echo "hello-world" | tr "hello-world" "Hello World"

Returns Heddd-ddddd. I want it to return Hello World. I believe this is because tr is interpreting the SET1 argument as a range (from the tr manpage):

CHAR1-CHAR2
    all characters from CHAR1 to CHAR2 in ascending order

I have also tried:

echo ${"hello-world//hello-world/Hello World"}

Which returns:

bash: ${"hello-world//hello-world/Hello World"}: bad substitution

What is the preferred way to do this (translate all instances of a string to a different string)? Either with tr or another program.

  • 2
    put the hyphen at the end: echo 'hello-world' | tr 'hw-' 'HW ' – mosvy Dec 26 '18 at 17:58
  • @mosvy Thanks. This was just a simple example - what should I do when I have a more complex string with other instances of h/w/- that I don't want to affect? I've update the title to better reflect the actual problem - tr was just one approach I have tried. – Frayt Dec 26 '18 at 18:04
  • 2
    tr is for mapping one-to-one between sets of characters - for string replacements, you should use something like sed – steeldriver Dec 26 '18 at 18:08
  • ... your shell parameter expansion approach would also work, provided your original string is inside a variable e.g. str="hello-world" ; echo "${str/hello-world/Hello World}" - it won't work on string literals AFAIK – steeldriver Dec 26 '18 at 18:23
2

Just we need to escape the -

echo "hello-world" | tr "hello\-world" "Hello World"

Luckily we don't have trailing h or w in the context to give a wired result. So, its better to replace the first char of each string to upper case.

Using sed

echo "hello-world" | sed 's/-/ /g;s/\<./\U&/g'
1

You can

  • convert the hyphens with tr
  • convert the first letter in each word to upper case (and print the rest of each word ($i,2) without any conversion) with awk

    $ echo 'hello-world-peace' | tr '-' ' ' | \
     awk '{for(i=1;i<=NF;i++){ $i=toupper(substr($i,1,1)) substr($i,2) }} {print}'
    Hello World Peace
    

You can also use awk for the whole task,

  • convert the hyphens with gsub
  • convert the first letter in each word to upper case with toupper
  • and print the rest of each word ($i,2) without any conversion

    echo 'hello-world-peace' | \
     awk '{gsub("-"," "); for(i=1;i<=NF;i++) \
     { $i=toupper(substr($i,1,1)) substr($i,2) }} {print}'
    
0

This sed would work:

echo "hello-world" |sed -E -n 's/.(.*)-.(.*)/H\1 W\2/p'

Output:

Hello World

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