How can I strip first X characters from string using sed

Question

I am writing shell script for embedded Linux in a small industrial box  I have a variable containing the text pid  1234 and I want to strip first X characters from the line  so only 1234 stays  I have more variables I need to  clean   so I need to cut away X first characters and   string 5  doesn t work for some reason in my system   The only thing the box seems to have is sed   I am trying to make the following to work   result   echo   pid    sed  s     4    g     Any ideas

User · Answer

Well  there have been solutions here with sed  awk  cut and using bash syntax  I just want to throw in another POSIX conform variant     echo  pid  1234    tail -c  6 1234   -c tells tail at which byte offset to start  counting from the end of the input data  yet if the the number starts with a   sign  it is from the beginning of the input data to the end

User · Answer

The following should work   var  pid  1234  var   var 5    Are you sure bash is the shell executing your script   Even the POSIX-compliant  var   var          would be preferable to using an external process  although this requires you to hard-code the 5 in the form of a fixed-length pattern

User · Answer

Another way  using cut instead of sed   result  echo  pid   cut -c 5-

User · Answer

I found the answer in pure sed supplied by this question  admittedly  posted after this question was posted    This does exactly what you asked  solely in sed  result   echo  quot  pid quot    sed        s pid     g         The dot in sed       is whatever you want to match  Your question is exactly what I was attempting to  except in my case I wanted to match a specific line in a file and then uncomment it   In my case it was    Uncomment a line  edit the file in-place   sed -i      COMMENTED LINE TO MATCH    s      g      path to target file  The -i after sed is to edit the file in place  remove this switch if you want to test your matching expression prior to editing the file    I posted this because I wanted to do this entirely with sed as this question asked and none of the previous answered solved that problem

User · Answer

This will do the job too   echo   pid  awk   print  2

User · Answer

Cut first two characters from string     string  1234567890   echo    string 2   34567890

User · Answer

Here s a concise method to cut the first X characters using cut 1   This example removes the first 4 characters by cutting a substring starting with 5th character   echo   pid    cut -c 5-

User · Answer

Chances are  you ll have cut as well  If so    me home   echo  pid  1234    cut -d    -f2 1234

User · Answer

pipe it through awk   print substr  0 42    where 42 is one more than the number of characters to drop  For example     echo abcde  awk   print substr  0 2    bcde

User · Answer

Rather than removing n characters from the start  perhaps you could just extract the digits directly  Like so       echo  pid  1234    grep -Po   d     This may be a more robust solution  and seems more intuitive

User · Answer

Use the -r option   use extended regular expressions in the script   to sed in order to use the  n  syntax     echo  pid  1234   sed -r  s    5     1234

[bash] How can I strip first X characters from string using sed?

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