How to remove last n characters from a string in Bash

Question

I have a variable var in a Bash script holding a string  like   echo  var  some string rtf    I want to remove the last 4 characters of this string and assign the result to a new variable var2  so that  echo  var2  some string    How can I do this

User · Answer

You can do like this      bin bash  v  some string rtf   v2   v  -4   echo   v -- gt   v2

User · Answer

In this case you could use basename assuming you have the same suffix on the files you want to remove   Example   basename -s  rtf  some string rtf       This will return  some string    If you don t know the suffix  and want it to remove everything after and including the last dot   f file whateverthisis basename    f           outputs  file      means chop    is what you are chopping    is wildcard

User · Answer

Using Variable expansion Substring replacement     var  Pattern Replacement  If suffix of var matches Pattern  then substitute Replacement for Pattern   So you can do     echo   var         some string  Alternatively  If you have always the same 4 letters    echo   var  rtf   some string  If it s always ending in  xyz     echo   var     some string  You can also use the length of the string     len    var     echo   var  len-4  some string  or simply echo   var  -4

User · Answer

What worked for me was  echo  quot hello world quot    rev   cut -c5-   rev   hello w  But I used it to trim lines in a file so that s why it looks awkward  The real use was  cat somefile   rev   cut -c5-   rev  cut only gets you as far as trimming from some starting position  which is bad if you need variable length rows  So this solution reverses  rev  the string and now we relate to its ending position  then uses cut as mentioned  and reverses  again  rev  it back to its original order

User · Answer

This worked for me by calculating size of string  It is easy you need to echo the value you need to return and then store it like below     removechars            var  some string rtf          size    var          echo   var 0 size-4              removechars     var2         some string

User · Answer

First  it s usually better to be explicit about your intent  So if you know the string ends in  rtf  and you want to remove that  rtf  you can just use var2   var  rtf   One potentially-useful aspect of this approach is that if the string doesn t end in  rtf  it is not changed at all  var2 will contain an unmodified copy of var  If you want to remove a filename suffix but don t know or care exactly what it is  you can use var2   var     to remove everything starting with the last    Or  if you only want to keep everything up to but not including the first    you can use var2   var       Those options have the same result if there s only one    but if there might be more than one  you get to pick which end of the string to work from  On the other hand  if there s no   in the string at all  var2 will again be an unchanged copy of var  If you really want to always remove a specific number of characters  here are some options  You tagged this bash specifically  so we ll start with bash builtins  The one which has worked the longest is the same suffix-removal syntax I used above  to remove four characters  use var2   var        Or to remove four characters only if the first one is a dot  use var2   var        which is like var2   var     but only removes the suffix if the part after the dot is exactly three characters  As you can see  to count characters this way  you need one question mark per unknown character removed  so this approach gets unwieldy for larger substring lengths  An option in newer shell versions is substring extraction  var2   var 0    var -4   Here you can put any number in place of the 4 to remove a different number of characters  The    var  is replaced by the length of the string  so this is actually asking to extract and keep  length - 4  characters starting with the first one  at index 0   With this approach  you lose the option to make the change only if the string matches a pattern  no matter what the actual value of the string is  the copy will include all but its last four characters  Bash lets you leave the start index out  it defaults to 0  so you can shorten that to just var2   var     var -4   In fact  newer versions of bash  specifically 4   which means the one that ships with MacOS won t work  recognize negative lengths as end indexes counting back from the end of the string  so you can get rid of the string-length expression  too  var2   var  -4   If you re not actually using bash but some other POSIX-type shell  the pattern-based suffix removal with   will still work     even in plain old dash  where the index-based substring extraction won t  Ksh and zsh do both support substring extraction  but require the explicit 0 start index  zsh also supports the negative end index  while ksh requires the length expression  Note that zsh  which indexes arrays starting at 1  nonetheless indexes strings starting at 0 if you use this bash-compatible syntax  but you can also treat parameters as arrays of characters  in which case it uses a 1-based count and expects a start and inclusive end position in brackets  var2  var 1 -5   Instead of using built-in shell parameter expansion  you can of course run some utility program to modify the string and capture its output with command substitution  There are several commands that will work  one is var2   sed  s    4        lt  lt  lt  quot  var quot

User · Answer

You could use sed   sed  s    4        lt  lt  lt    var    EXample     var  some string rtf    var1   sed  s    4        lt  lt  lt    var     echo  var1 some string

User · Answer

Hope the below example will help   echo   name 0       name -10    --    name start len    In above command  name is the variable  start is the string starting point len is the length of string that has to be removed    Example       read -p  Enter   name     echo   name 0       name -10      Output       Enter Siddharth Murugan     Siddhar   Note  Bash 4 2 added support for negative substring

User · Answer

I tried the following and it worked for me       bin bash  var  hello c  length    var  endindex   expr  length - 4  echo   var 0  endindex    Output  hel

User · Answer

To remove four characters from the end of the string use   var         To remove everything after the final   use   var

[bash] How to remove last n characters from a string in Bash?

Examples related to bash