I have a string like AxxBCyyyDEFzzLMN and I want to replace all the occurrences of x, y, and z with _.
How can I achieve this?
I know that echo "$string" | tr 'x' '_' | tr 'y' '_' would work, but I want to do that in one go, without using pipes.
5 Answers
echo "$string" | tr xyz _ would replace each occurrence of x, y, or z with _, giving A__BC___DEF__LMN in your example.
echo "$string" | sed -r 's/[xyz]+/_/g' would replace repeating occurrences of x, y, or z with a single _, giving A_BC_DEF_LMN in your example.
Using Bash Parameter Expansion:
orig="AxxBCyyyDEFzzLMN" mod=${orig//[xyz]/_} You might find this link helpful: .
In general, to replace the first match of $substring with $replacement:
${string/substring/replacement} To replace all matches of $substring with $replacement:
${string//substring/replacement} EDIT: Note that this applies to a variable named $string.
Here is a solution with shell parameter expansion that replaces multiple contiguous occurrences with a single _:
$ var=AxxBCyyyDEFzzLMN $ echo "${var//+([xyz])/_}" A_BC_DEF_LMN Notice that the +(pattern) pattern requires extended pattern matching, turned on with
shopt -s extglob Alternatively, with the -s ("squeeze") option of tr:
$ tr -s xyz _ <<< "$var" A_BC_DEF_LMN read filename ; sed -i 's/letter/newletter/g' "$filename" #letter ^use as many of these as you need, and you can make your own BASIC encryption
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