CODEWITHSUNDEEP
regexsed
Adam Matan
Adam Matan

Reputation: 136181

sed: replace from the last occurrence of "-" till EOL

My problem

I have a file with items, one per line. The item contains at least one dash, and I would like to remove the last dash and the words that follow. For example:

item asdkalqndla-asdnkfsv-324we-blueray
item asda-vbght564e-dfg-redapple
item gefdsc-fgy-543-5trr-floatingvanilla

Should give:

item asdkalqndla-asdnkfsv-324we
item asda-vbght564e-dfg
item gefdsc-fgy-543-5trr

What have I tried

sed 's/\-.*$//' lines.txt

Which gives

item asdkalqndla
item asda
item gefdsc

Because the regex is greedy, and consumes everything from the first dash onwards.

My question

How can I remove all characters from the last - in a string till EOL?

Upvotes: 2

Views: 221

Answers (4)

potong
potong

Reputation: 58391

This might work for you (GNU sed):

sed 's/\(.*\)-.*/\1/' file

Used greed to find the last - and replace the whole line with what came before it.

Upvotes: 1

RavinderSingh13
RavinderSingh13

Reputation: 133458

Following simple awk may help you in same.

awk -F"-" 'NF{NF=(NF-1)} 1' OFS="-"   Input_file

Output will be as follows.

item asdkalqndla-asdnkfsv-324we
item asda-vbght564e-dfg
item gefdsc-fgy-543-5trr

Explanation: -F"-": Making field separator as - for each line for Input_file.

NF{NF=(NF-1)}: awk has out of the box NF variable which has number of fields for any line, since we don't text after last occurrence of - and field separator is -, by mentioning NF, we are checking if a line is NOT EMPTY. decrementing the number of field's value with 1 so that we will NOT get the last field.

1: awk works on method of condition then action so making condition part TRUE here by mentioning 1 here and not mentioning any action here so by default print of current line will happen.

OFS="-": Making OFS output field separator as "-" here so that - will come in output.

EDIT: Shorter versions of decrementing NF too as follows.

awk -F"-" 'NF{NF-=1} 1' OFS="-"  Input_file

OR

awk -F"-" 'NF{NF--} 1' OFS="-"  Input_file

Upvotes: 2

dawg
dawg

Reputation: 103814

With awk:

$ awk '{sub(/-[^-]*$/,""); print}' file
item asdkalqndla-asdnkfsv-324we
item asda-vbght564e-dfg
item gefdsc-fgy-543-5trr

Upvotes: 3

Adam Matan
Adam Matan

Reputation: 136181

Simple negation using ^\- solved the problem:

$ sed 's/\-[^\-]*$//' lines.txt
item asdkalqndla-asdnkfsv-324we
item asda-vbght564e-dfg
item gefdsc-fgy-543-5trr

This way, sed replaces a dash followed by anything-but-dash till the end of the line.

Upvotes: 2

Related Questions