strip all from line starting after whitespace












1















I have a file with this content:



lines
lines
rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s / ext4 defaults,
lines


I am searching for one line command which should strip everything in the line rootdev after whitespace, so the final content should be like:



lines
lines
rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s
lines


Any idea how to do it with one line command? (so I do not need to open nano with this file and do it manually)



I tried with sed but it just replaces the word rootdev



sed -i 's/rootdev//g' file.txt









share|improve this question





























    1















    I have a file with this content:



    lines
    lines
    rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s / ext4 defaults,
    lines


    I am searching for one line command which should strip everything in the line rootdev after whitespace, so the final content should be like:



    lines
    lines
    rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s
    lines


    Any idea how to do it with one line command? (so I do not need to open nano with this file and do it manually)



    I tried with sed but it just replaces the word rootdev



    sed -i 's/rootdev//g' file.txt









    share|improve this question



























      1












      1








      1








      I have a file with this content:



      lines
      lines
      rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s / ext4 defaults,
      lines


      I am searching for one line command which should strip everything in the line rootdev after whitespace, so the final content should be like:



      lines
      lines
      rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s
      lines


      Any idea how to do it with one line command? (so I do not need to open nano with this file and do it manually)



      I tried with sed but it just replaces the word rootdev



      sed -i 's/rootdev//g' file.txt









      share|improve this question
















      I have a file with this content:



      lines
      lines
      rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s / ext4 defaults,
      lines


      I am searching for one line command which should strip everything in the line rootdev after whitespace, so the final content should be like:



      lines
      lines
      rootdev=UUID=967d8dc3-f595-4a6e-929e-cc89as5a1a2s
      lines


      Any idea how to do it with one line command? (so I do not need to open nano with this file and do it manually)



      I tried with sed but it just replaces the word rootdev



      sed -i 's/rootdev//g' file.txt






      linux sed sh






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 21 '18 at 12:24









      Inian

      40.8k64172




      40.8k64172










      asked Nov 21 '18 at 11:59









      peterpeter

      1,44552348




      1,44552348
























          2 Answers
          2






          active

          oldest

          votes


















          2














          Your attempt with sed can't work because it would just remove rootdev string with an empty string. What you need is a tool that matches a pattern and does an action on that whole line for which I think awk is more recommended than sed.



          Using awk to match the line to strip off the spaces using gsub() should be sufficient,



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          If you are using GNU awk with version greater than 4.1.0, you could use its in-place edit option to make the changes dynamically



          gawk -i inplace '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          for earlier versions, use a temporary file



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file > temp && mv temp file


          or use sponge from moreutils. If its not available in your system do get it on RHEL using yum install moreutils or with apt-get in Debian.



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file | sponge file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41



















          1














          First, search for a line beginning with rootdev=, and when you find it delete everything after the first whitespace until the end of line.



          sed -i '/^rootdev=/ s/ .*$//' file


          Using a capturing group to keep rootdev=... part in, and replacing the whole line with it is an option too.



          sed -i 's/^(rootdev=[^ ]*).*$/1/' file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41











          • Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

            – oguzismail
            Nov 22 '18 at 14:02











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          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2














          Your attempt with sed can't work because it would just remove rootdev string with an empty string. What you need is a tool that matches a pattern and does an action on that whole line for which I think awk is more recommended than sed.



          Using awk to match the line to strip off the spaces using gsub() should be sufficient,



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          If you are using GNU awk with version greater than 4.1.0, you could use its in-place edit option to make the changes dynamically



          gawk -i inplace '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          for earlier versions, use a temporary file



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file > temp && mv temp file


          or use sponge from moreutils. If its not available in your system do get it on RHEL using yum install moreutils or with apt-get in Debian.



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file | sponge file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41
















          2














          Your attempt with sed can't work because it would just remove rootdev string with an empty string. What you need is a tool that matches a pattern and does an action on that whole line for which I think awk is more recommended than sed.



          Using awk to match the line to strip off the spaces using gsub() should be sufficient,



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          If you are using GNU awk with version greater than 4.1.0, you could use its in-place edit option to make the changes dynamically



          gawk -i inplace '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          for earlier versions, use a temporary file



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file > temp && mv temp file


          or use sponge from moreutils. If its not available in your system do get it on RHEL using yum install moreutils or with apt-get in Debian.



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file | sponge file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41














          2












          2








          2







          Your attempt with sed can't work because it would just remove rootdev string with an empty string. What you need is a tool that matches a pattern and does an action on that whole line for which I think awk is more recommended than sed.



          Using awk to match the line to strip off the spaces using gsub() should be sufficient,



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          If you are using GNU awk with version greater than 4.1.0, you could use its in-place edit option to make the changes dynamically



          gawk -i inplace '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          for earlier versions, use a temporary file



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file > temp && mv temp file


          or use sponge from moreutils. If its not available in your system do get it on RHEL using yum install moreutils or with apt-get in Debian.



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file | sponge file





          share|improve this answer















          Your attempt with sed can't work because it would just remove rootdev string with an empty string. What you need is a tool that matches a pattern and does an action on that whole line for which I think awk is more recommended than sed.



          Using awk to match the line to strip off the spaces using gsub() should be sufficient,



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          If you are using GNU awk with version greater than 4.1.0, you could use its in-place edit option to make the changes dynamically



          gawk -i inplace '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file


          for earlier versions, use a temporary file



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file > temp && mv temp file


          or use sponge from moreutils. If its not available in your system do get it on RHEL using yum install moreutils or with apt-get in Debian.



          awk '/^rootdev/{ gsub(/[[:space:]].*/,"",$0) }1' file | sponge file






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Nov 21 '18 at 13:45

























          answered Nov 21 '18 at 12:07









          InianInian

          40.8k64172




          40.8k64172













          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41



















          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41

















          hi, in my case it does not work (file content stays the same).

          – peter
          Nov 22 '18 at 12:20





          hi, in my case it does not work (file content stays the same).

          – peter
          Nov 22 '18 at 12:20













          what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

          – peter
          Nov 22 '18 at 12:33





          what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

          – peter
          Nov 22 '18 at 12:33













          I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

          – peter
          Nov 22 '18 at 12:41





          I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

          – peter
          Nov 22 '18 at 12:41













          1














          First, search for a line beginning with rootdev=, and when you find it delete everything after the first whitespace until the end of line.



          sed -i '/^rootdev=/ s/ .*$//' file


          Using a capturing group to keep rootdev=... part in, and replacing the whole line with it is an option too.



          sed -i 's/^(rootdev=[^ ]*).*$/1/' file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41











          • Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

            – oguzismail
            Nov 22 '18 at 14:02
















          1














          First, search for a line beginning with rootdev=, and when you find it delete everything after the first whitespace until the end of line.



          sed -i '/^rootdev=/ s/ .*$//' file


          Using a capturing group to keep rootdev=... part in, and replacing the whole line with it is an option too.



          sed -i 's/^(rootdev=[^ ]*).*$/1/' file





          share|improve this answer


























          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41











          • Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

            – oguzismail
            Nov 22 '18 at 14:02














          1












          1








          1







          First, search for a line beginning with rootdev=, and when you find it delete everything after the first whitespace until the end of line.



          sed -i '/^rootdev=/ s/ .*$//' file


          Using a capturing group to keep rootdev=... part in, and replacing the whole line with it is an option too.



          sed -i 's/^(rootdev=[^ ]*).*$/1/' file





          share|improve this answer















          First, search for a line beginning with rootdev=, and when you find it delete everything after the first whitespace until the end of line.



          sed -i '/^rootdev=/ s/ .*$//' file


          Using a capturing group to keep rootdev=... part in, and replacing the whole line with it is an option too.



          sed -i 's/^(rootdev=[^ ]*).*$/1/' file






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Nov 21 '18 at 14:23

























          answered Nov 21 '18 at 12:24









          oguzismailoguzismail

          3,76031226




          3,76031226













          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41











          • Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

            – oguzismail
            Nov 22 '18 at 14:02



















          • hi, in my case it does not work (file content stays the same).

            – peter
            Nov 22 '18 at 12:20











          • what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

            – peter
            Nov 22 '18 at 12:33











          • I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

            – peter
            Nov 22 '18 at 12:41











          • Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

            – oguzismail
            Nov 22 '18 at 14:02

















          hi, in my case it does not work (file content stays the same).

          – peter
          Nov 22 '18 at 12:20





          hi, in my case it does not work (file content stays the same).

          – peter
          Nov 22 '18 at 12:20













          what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

          – peter
          Nov 22 '18 at 12:33





          what I tried - to use "cut" program and strip everything from char 50. But now I have no idea how to save output of cut to file.

          – peter
          Nov 22 '18 at 12:33













          I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

          – peter
          Nov 22 '18 at 12:41





          I solved it with: sudo cut --complement -c50-999 file > file 2&& sudo mv file2 file

          – peter
          Nov 22 '18 at 12:41













          Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

          – oguzismail
          Nov 22 '18 at 14:02





          Both mine and Inian's solutions work with your example. Please see stackoverflow.com/help/mcve and edit your question accordingly if you want us to help you.

          – oguzismail
          Nov 22 '18 at 14:02


















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