Extract substring in Bash

Question

Given a filename in the form someletters 12345 moreleters ext  I want to extract the 5 digits and put them into a variable   So to emphasize the point  I have a filename with x number of characters then a five digit sequence surrounded by a single underscore on either side then another set of x number of characters   I want to take the 5 digit number and put that into a variable   I am very interested in the number of different ways that this can be accomplished

User · Answer

A bash solution   IFS     read -r x digs x  lt  lt  lt  someletters 12345 moreleters ext    This will clobber a variable called x  The var x could be changed to the var     input  someletters 12345 moreleters ext  IFS     read -r   digs    lt  lt  lt   input

User · Answer

Without any sub-processes you can   shopt -s extglob front   input      a-zA-Z      digits   front     a-zA-Z       A very small variant of this will also work in ksh93

User · Answer

Generic solution where the number can be anywhere in the filename  using the first of such sequences   number   echo  filename   egrep -o     digit    5     head -n1    Another solution to extract exactly a part of a variable   number   filename offset length    If your filename always have the format stuff digits     you can use awk   number   echo  filename   awk -F      print  2       Yet another solution to remove everything except digits  use  number   echo  filename   tr -cd     digit

User · Answer

I m surprised this pure bash solution didn t come up   a  someletters 12345 moreleters ext  IFS     set  a echo  2   prints 12345   You probably want to reset IFS to what value it was before  or unset IFS afterwards

User · Answer

Here s how i d do it   FN someletters 12345 moreleters ext      FN          digit    5        amp  amp  NUM   BASH REMATCH 1     Explanation   Bash-specific          indicates a conditional expression    indicates the condition is a regular expression  amp  amp  chains the commands if the prior command was successful   Regular Expressions  RE        digit    5        are literals to demarcate anchor matching boundaries for the string being matched    create a capture group    digit    is a character class  i think it speaks for itself  5  means exactly five of the prior character  class  as in this example   or group must match   In english  you can think of it behaving like this  the FN string is iterated character by character until we see an   at which point the capture group is opened and we attempt to match five digits  If that matching is successful to this point  the capture group saves the five digits traversed  If the next character is an    the condition is successful  the capture group is made available in BASH REMATCH  and the next NUM  statement can execute  If any part of the matching fails  saved details are disposed of and character by character processing continues after the    e g  if FN where  1  12  123  1234  12345   there would be four false starts before it found a match

User · Answer

Here s a prefix-suffix solution  similar to the solutions given by JB and Darron  that matches the first block of digits and does not depend on the surrounding underscores   str  someletters 12345 morele34ters ext  s1    str    str     digit             strip off non-digit prefix from str s2    s1      digit                    strip off non-digit suffix from s1 echo   s2                              12345

User · Answer

If x is constant  the following parameter expansion performs substring extraction   b   a 12 5    where 12 is the offset  zero-based  and 5 is the length  If the underscores around the digits are the only ones in the input  you can strip off the prefix and suffix  respectively  in two steps   tmp   a         remove prefix ending in     b   tmp         remove suffix starting with       If there are other underscores  it s probably feasible anyway  albeit more tricky   If anyone knows how to perform both expansions in a single expression  I d like to know too   Both solutions presented are pure bash  with no process spawning involved  hence very fast

User · Answer

Building on jor s answer  which doesn t work for me    substring   expr   filename

User · Answer

A bash solution   IFS     read -r x digs x  lt  lt  lt  someletters 12345 moreleters ext    This will clobber a variable called x  The var x could be changed to the var     input  someletters 12345 moreleters ext  IFS     read -r   digs    lt  lt  lt   input

User · Answer

Inklusive end  similar to JS and Java implementations  Remove  1 if you do not desire this  function substring         local str  quot  1 quot  start  quot   2  quot  end  quot   3  quot           if     quot  start quot      quot  quot      then start  quot 0 quot   fi     if     quot  end quot        quot  quot      then end  quot    str  quot   fi          local length  quot     end -  start  1   quot           echo  quot   str   start    length   quot      Example      substring 01234 0     01234     substring 012345 0     012345     substring 012345 0 0     0     substring 012345 1 1     1     substring 012345 1 2     12     substring 012345 0 1     01     substring 012345 0 2     012     substring 012345 0 3     0123     substring 012345 0 4     01234     substring 012345 0 5     012345  More example calls      substring 012345 0     012345     substring 012345 1     12345     substring 012345 2     2345     substring 012345 3     345     substring 012345 4     45     substring 012345 5     5     substring 012345 6          substring 012345 3 5     345     substring 012345 3 4     34     substring 012345 2 4     234     substring 012345 1 3     123

User · Answer

There s also the bash builtin  expr  command     INPUT  someletters 12345 moreleters ext    SUBSTRING  expr match   INPUT           digit               echo  SUBSTRING

User · Answer

Building on jor s answer  which doesn t work for me    substring   expr   filename

User · Answer

Following the requirements     I have a filename with x number of characters then a five digit   sequence surrounded by a single underscore on either side then another   set of x number of characters  I want to take the 5 digit number and   put that into a variable    I found some grep ways that may be useful     echo  someletters 12345 moreleters ext    grep -Eo     digit       12345   or better    echo  someletters 12345 moreleters ext    grep -Eo     digit    5    12345   And then with -Po syntax     echo  someletters 12345 moreleters ext    grep -Po     lt     d    12345   Or if you want to make it fit exactly 5 characters     echo  someletters 12345 moreleters ext    grep -Po     lt     d 5    12345   Finally  to make it be stored in a variable it is just need to use the var   command  syntax

User · Answer

Following the requirements     I have a filename with x number of characters then a five digit   sequence surrounded by a single underscore on either side then another   set of x number of characters  I want to take the 5 digit number and   put that into a variable    I found some grep ways that may be useful     echo  someletters 12345 moreleters ext    grep -Eo     digit       12345   or better    echo  someletters 12345 moreleters ext    grep -Eo     digit    5    12345   And then with -Po syntax     echo  someletters 12345 moreleters ext    grep -Po     lt     d    12345   Or if you want to make it fit exactly 5 characters     echo  someletters 12345 moreleters ext    grep -Po     lt     d 5    12345   Finally  to make it be stored in a variable it is just need to use the var   command  syntax

User · Answer

If we focus in the concept of       A run of  one or several  digits   We could use several external tools to extract the numbers  We could quite easily erase all other characters  either sed or tr   name  someletters 12345 moreleters ext   echo  name   sed  s   0-9    g       12345 echo  name   tr -c -d 0-9            12345   But if  name contains several runs of numbers  the above will fail   If  name someletters 12345 moreleters 323 end ext   then   echo  name   sed  s   0-9    g       12345323 echo  name   tr -c -d 0-9            12345323   We need to use regular expresions  regex   To select only the first run  12345 not 323  in sed and perl   echo  name   sed  s   0-9     0-9   1          1   perl -e  my  name   name  my   num   name     d    print   num n      But we could as well do it directly in bash 1     regex   0-9    0-9  1              name     regex     amp  amp  echo   BASH REMATCH 1     This allows us to extract the FIRST run of digits of any length surrounded by any other text characters     Note  regex   0-9    0-9  5 5       will match only exactly 5 digit runs   -    1    faster than calling an external tool for each short texts  Not faster than doing all processing inside sed or awk for large files

User · Answer

Here s how i d do it   FN someletters 12345 moreleters ext      FN          digit    5        amp  amp  NUM   BASH REMATCH 1     Explanation   Bash-specific          indicates a conditional expression    indicates the condition is a regular expression  amp  amp  chains the commands if the prior command was successful   Regular Expressions  RE        digit    5        are literals to demarcate anchor matching boundaries for the string being matched    create a capture group    digit    is a character class  i think it speaks for itself  5  means exactly five of the prior character  class  as in this example   or group must match   In english  you can think of it behaving like this  the FN string is iterated character by character until we see an   at which point the capture group is opened and we attempt to match five digits  If that matching is successful to this point  the capture group saves the five digits traversed  If the next character is an    the condition is successful  the capture group is made available in BASH REMATCH  and the next NUM  statement can execute  If any part of the matching fails  saved details are disposed of and character by character processing continues after the    e g  if FN where  1  12  123  1234  12345   there would be four false starts before it found a match

User · Answer

Here s how i d do it   FN someletters 12345 moreleters ext      FN          digit    5        amp  amp  NUM   BASH REMATCH 1     Explanation   Bash-specific          indicates a conditional expression    indicates the condition is a regular expression  amp  amp  chains the commands if the prior command was successful   Regular Expressions  RE        digit    5        are literals to demarcate anchor matching boundaries for the string being matched    create a capture group    digit    is a character class  i think it speaks for itself  5  means exactly five of the prior character  class  as in this example   or group must match   In english  you can think of it behaving like this  the FN string is iterated character by character until we see an   at which point the capture group is opened and we attempt to match five digits  If that matching is successful to this point  the capture group saves the five digits traversed  If the next character is an    the condition is successful  the capture group is made available in BASH REMATCH  and the next NUM  statement can execute  If any part of the matching fails  saved details are disposed of and character by character processing continues after the    e g  if FN where  1  12  123  1234  12345   there would be four false starts before it found a match

User · Answer

similar to substr  abcdefg   2-1  3  in php   echo  abcdefg  tail -c  2 head -c 3

User · Answer

Building on jor s answer  which doesn t work for me    substring   expr   filename

User · Answer

I m surprised this pure bash solution didn t come up   a  someletters 12345 moreleters ext  IFS     set  a echo  2   prints 12345   You probably want to reset IFS to what value it was before  or unset IFS afterwards

User · Answer

Generic solution where the number can be anywhere in the filename  using the first of such sequences   number   echo  filename   egrep -o     digit    5     head -n1    Another solution to extract exactly a part of a variable   number   filename offset length    If your filename always have the format stuff digits     you can use awk   number   echo  filename   awk -F      print  2       Yet another solution to remove everything except digits  use  number   echo  filename   tr -cd     digit

User · Answer

In case someone wants more rigorous information  you can also search it in man bash like this    man bash  press return key   substring   press return key   press  n  key   press  n  key   press  n  key   press  n  key    Result      parameter offset           parameter offset length                Substring Expansion   Expands to  up  to  length  characters  of               parameter  starting  at  the  character specified by offset   If               length is omitted  expands to the substring of parameter  start-               ing at the character specified by offset   length and offset are               arithmetic expressions  see ARITHMETIC  EVALUATION  below     If               offset  evaluates  to a number less than zero  the value is used               as an offset from the end of the value of parameter   Arithmetic               expressions  starting  with  a - must be separated by whitespace               from the preceding   to be distinguished from  the  Use  Default               Values  expansion    If  length  evaluates to a number less than               zero  and parameter is not   and not an indexed  or  associative               array   it is interpreted as an offset from the end of the value               of parameter rather than a number of characters  and the  expan-               sion is the characters between the two offsets   If parameter is                  the result is length positional parameters beginning at  off-               set    If parameter is an indexed array name subscripted by   or                  the result is the length members of the array beginning  with                 parameter offset      A  negative  offset is taken relative to               one greater than the maximum index of the specified array   Sub-               string  expansion applied to an associative array produces unde-               fined results   Note that a negative offset  must  be  separated               from  the  colon  by  at least one space to avoid being confused               with the  - expansion   Substring indexing is zero-based  unless               the  positional  parameters are used  in which case the indexing               starts at 1 by default   If offset  is  0   and  the  positional               parameters are used   0 is prefixed to the list

User · Answer

Here s a prefix-suffix solution  similar to the solutions given by JB and Darron  that matches the first block of digits and does not depend on the surrounding underscores   str  someletters 12345 morele34ters ext  s1    str    str     digit             strip off non-digit prefix from str s2    s1      digit                    strip off non-digit suffix from s1 echo   s2                              12345

User · Answer

Generic solution where the number can be anywhere in the filename  using the first of such sequences   number   echo  filename   egrep -o     digit    5     head -n1    Another solution to extract exactly a part of a variable   number   filename offset length    If your filename always have the format stuff digits     you can use awk   number   echo  filename   awk -F      print  2       Yet another solution to remove everything except digits  use  number   echo  filename   tr -cd     digit

User · Answer

just try to use cut -c startIndx-stopIndx

User · Answer

Ok  here goes pure Parameter Substitution with an empty string  Caveat is that I have defined someletters and moreletters as only characters  If they are alphanumeric  this will not work as it is   filename someletters 12345 moreletters ext substring   filename       a-z        a-z       echo  substring 12345

User · Answer

If x is constant  the following parameter expansion performs substring extraction   b   a 12 5    where 12 is the offset  zero-based  and 5 is the length  If the underscores around the digits are the only ones in the input  you can strip off the prefix and suffix  respectively  in two steps   tmp   a         remove prefix ending in     b   tmp         remove suffix starting with       If there are other underscores  it s probably feasible anyway  albeit more tricky   If anyone knows how to perform both expansions in a single expression  I d like to know too   Both solutions presented are pure bash  with no process spawning involved  hence very fast

User · Answer

Here s how i d do it   FN someletters 12345 moreleters ext      FN          digit    5        amp  amp  NUM   BASH REMATCH 1     Explanation   Bash-specific          indicates a conditional expression    indicates the condition is a regular expression  amp  amp  chains the commands if the prior command was successful   Regular Expressions  RE        digit    5        are literals to demarcate anchor matching boundaries for the string being matched    create a capture group    digit    is a character class  i think it speaks for itself  5  means exactly five of the prior character  class  as in this example   or group must match   In english  you can think of it behaving like this  the FN string is iterated character by character until we see an   at which point the capture group is opened and we attempt to match five digits  If that matching is successful to this point  the capture group saves the five digits traversed  If the next character is an    the condition is successful  the capture group is made available in BASH REMATCH  and the next NUM  statement can execute  If any part of the matching fails  saved details are disposed of and character by character processing continues after the    e g  if FN where  1  12  123  1234  12345   there would be four false starts before it found a match

User · Answer

My answer will have more control on what you want out of your string  Here is the code on how you can extract 12345 out of your string  str  someletters 12345 moreleters ext  str   str     str   str  more   echo  str   This will be more efficient if you want to extract something that has any chars like abc or any special characters like   or -  For example  If your string is like this and you want everything that is after someletters  and before  moreleters ext    str  someletters 123-45-24a amp 13b-1 moreleters ext    With my code you can mention what exactly you want  Explanation      It will remove the preceding string including the matching key  Here the key we mentioned is      It will remove the following string including the matching key  Here the key we mentioned is   more    Do some experiments yourself and you would find this interesting

User · Answer

Generic solution where the number can be anywhere in the filename  using the first of such sequences   number   echo  filename   egrep -o     digit    5     head -n1    Another solution to extract exactly a part of a variable   number   filename offset length    If your filename always have the format stuff digits     you can use awk   number   echo  filename   awk -F      print  2       Yet another solution to remove everything except digits  use  number   echo  filename   tr -cd     digit

User · Answer

Without any sub-processes you can   shopt -s extglob front   input      a-zA-Z      digits   front     a-zA-Z       A very small variant of this will also work in ksh93

User · Answer

shell cut - print specific range of characters or given part from a string  method1  using bash  str 2020-08-08T07 40 00 000Z  echo   str 11 8    method2  using cut  str 2020-08-08T07 40 00 000Z  cut -c12-19  lt  lt  lt   str   method3  when working with awk  str 2020-08-08T07 40 00 000Z  awk   time gensub    11    8       quot   1 quot   quot g quot   1   print time    lt  lt  lt   str

User · Answer

Building on jor s answer  which doesn t work for me    substring   expr   filename

User · Answer

Use cut   echo  someletters 12345 moreleters ext    cut -d    -f 2   More generic   INPUT  someletters 12345 moreleters ext  SUBSTRING   echo  INPUT  cut -d    -f 2  echo  SUBSTRING

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A little late  but I just ran across this problem and found the following   host  tmp  asd someletters 12345 moreleters ext  host  tmp  echo  expr  asd                 12345 host  tmp     I used it to get millisecond resolution on an embedded system that does not have  N for date   set  grep  now at   proc timer list  nano  3 fraction  expr  nano                       debug nano is  nano  fraction is  fraction

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Given test txt is a file containing  ABCDEFGHIJKLMNOPQRSTUVWXYZ   cut -b19-20 test txt  gt  test1 txt   This will extract chars 19  amp  20  ST   while read -r  do   gt  x  REPLY  gt  done  lt  test1 txt echo  x ST

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In case someone wants more rigorous information  you can also search it in man bash like this    man bash  press return key   substring   press return key   press  n  key   press  n  key   press  n  key   press  n  key    Result      parameter offset           parameter offset length                Substring Expansion   Expands to  up  to  length  characters  of               parameter  starting  at  the  character specified by offset   If               length is omitted  expands to the substring of parameter  start-               ing at the character specified by offset   length and offset are               arithmetic expressions  see ARITHMETIC  EVALUATION  below     If               offset  evaluates  to a number less than zero  the value is used               as an offset from the end of the value of parameter   Arithmetic               expressions  starting  with  a - must be separated by whitespace               from the preceding   to be distinguished from  the  Use  Default               Values  expansion    If  length  evaluates to a number less than               zero  and parameter is not   and not an indexed  or  associative               array   it is interpreted as an offset from the end of the value               of parameter rather than a number of characters  and the  expan-               sion is the characters between the two offsets   If parameter is                  the result is length positional parameters beginning at  off-               set    If parameter is an indexed array name subscripted by   or                  the result is the length members of the array beginning  with                 parameter offset      A  negative  offset is taken relative to               one greater than the maximum index of the specified array   Sub-               string  expansion applied to an associative array produces unde-               fined results   Note that a negative offset  must  be  separated               from  the  colon  by  at least one space to avoid being confused               with the  - expansion   Substring indexing is zero-based  unless               the  positional  parameters are used  in which case the indexing               starts at 1 by default   If offset  is  0   and  the  positional               parameters are used   0 is prefixed to the list

User · Answer

Inklusive end  similar to JS and Java implementations  Remove  1 if you do not desire this  function substring         local str  quot  1 quot  start  quot   2  quot  end  quot   3  quot           if     quot  start quot      quot  quot      then start  quot 0 quot   fi     if     quot  end quot        quot  quot      then end  quot    str  quot   fi          local length  quot     end -  start  1   quot           echo  quot   str   start    length   quot      Example      substring 01234 0     01234     substring 012345 0     012345     substring 012345 0 0     0     substring 012345 1 1     1     substring 012345 1 2     12     substring 012345 0 1     01     substring 012345 0 2     012     substring 012345 0 3     0123     substring 012345 0 4     01234     substring 012345 0 5     012345  More example calls      substring 012345 0     012345     substring 012345 1     12345     substring 012345 2     2345     substring 012345 3     345     substring 012345 4     45     substring 012345 5     5     substring 012345 6          substring 012345 3 5     345     substring 012345 3 4     34     substring 012345 2 4     234     substring 012345 1 3     123

User · Answer

My answer will have more control on what you want out of your string  Here is the code on how you can extract 12345 out of your string  str  someletters 12345 moreleters ext  str   str     str   str  more   echo  str   This will be more efficient if you want to extract something that has any chars like abc or any special characters like   or -  For example  If your string is like this and you want everything that is after someletters  and before  moreleters ext    str  someletters 123-45-24a amp 13b-1 moreleters ext    With my code you can mention what exactly you want  Explanation      It will remove the preceding string including the matching key  Here the key we mentioned is      It will remove the following string including the matching key  Here the key we mentioned is   more    Do some experiments yourself and you would find this interesting

User · Answer

If x is constant  the following parameter expansion performs substring extraction   b   a 12 5    where 12 is the offset  zero-based  and 5 is the length  If the underscores around the digits are the only ones in the input  you can strip off the prefix and suffix  respectively  in two steps   tmp   a         remove prefix ending in     b   tmp         remove suffix starting with       If there are other underscores  it s probably feasible anyway  albeit more tricky   If anyone knows how to perform both expansions in a single expression  I d like to know too   Both solutions presented are pure bash  with no process spawning involved  hence very fast

User · Answer

Use cut   echo  someletters 12345 moreleters ext    cut -d    -f 2   More generic   INPUT  someletters 12345 moreleters ext  SUBSTRING   echo  INPUT  cut -d    -f 2  echo  SUBSTRING

User · Answer

There s also the bash builtin  expr  command     INPUT  someletters 12345 moreleters ext    SUBSTRING  expr match   INPUT           digit               echo  SUBSTRING

User · Answer

Use cut   echo  someletters 12345 moreleters ext    cut -d    -f 2   More generic   INPUT  someletters 12345 moreleters ext  SUBSTRING   echo  INPUT  cut -d    -f 2  echo  SUBSTRING

User · Answer

I love sed s capability to deal with regex groups    gt  var  someletters 12345 moreletters ext   gt  digits    echo  var   sed  s       0-9         1 p  -n    gt  echo  digits 12345   A slightly more general option would be not to assume that you have an underscore   marking the start of your digits sequence  hence for instance stripping off all non-numbers you get before your sequence  s   0-9      0-9         1 p      gt  man sed   grep s regexp replacement -A 2 s regexp replacement      Attempt to match regexp against the pattern space   If successful  replace that portion matched with replacement   The replacement may contain the special  character   amp   to     refer to that portion of the pattern space which matched  and the special escapes  1 through  9 to refer to the corresponding matching sub-expressions in the regexp      More on this  in case you re not too confident with regexps    s is for  s ubstitute  0-9   matches 1  digits  1 links to the group n 1 of the regex output  group 0 is the whole match  group 1 is the match within parentheses in this case  p flag is for  p rinting   All escapes   are there to make sed s regexp processing work

User · Answer

Without any sub-processes you can   shopt -s extglob front   input      a-zA-Z      digits   front     a-zA-Z       A very small variant of this will also work in ksh93

User · Answer

A little late  but I just ran across this problem and found the following   host  tmp  asd someletters 12345 moreleters ext  host  tmp  echo  expr  asd                 12345 host  tmp     I used it to get millisecond resolution on an embedded system that does not have  N for date   set  grep  now at   proc timer list  nano  3 fraction  expr  nano                       debug nano is  nano  fraction is  fraction

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If we focus in the concept of       A run of  one or several  digits   We could use several external tools to extract the numbers  We could quite easily erase all other characters  either sed or tr   name  someletters 12345 moreleters ext   echo  name   sed  s   0-9    g       12345 echo  name   tr -c -d 0-9            12345   But if  name contains several runs of numbers  the above will fail   If  name someletters 12345 moreleters 323 end ext   then   echo  name   sed  s   0-9    g       12345323 echo  name   tr -c -d 0-9            12345323   We need to use regular expresions  regex   To select only the first run  12345 not 323  in sed and perl   echo  name   sed  s   0-9     0-9   1          1   perl -e  my  name   name  my   num   name     d    print   num n      But we could as well do it directly in bash 1     regex   0-9    0-9  1              name     regex     amp  amp  echo   BASH REMATCH 1     This allows us to extract the FIRST run of digits of any length surrounded by any other text characters     Note  regex   0-9    0-9  5 5       will match only exactly 5 digit runs   -    1    faster than calling an external tool for each short texts  Not faster than doing all processing inside sed or awk for large files

User · Answer

There s also the bash builtin  expr  command     INPUT  someletters 12345 moreleters ext    SUBSTRING  expr match   INPUT           digit               echo  SUBSTRING

User · Answer

just try to use cut -c startIndx-stopIndx

User · Answer

Ok  here goes pure Parameter Substitution with an empty string  Caveat is that I have defined someletters and moreletters as only characters  If they are alphanumeric  this will not work as it is   filename someletters 12345 moreletters ext substring   filename       a-z        a-z       echo  substring 12345

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Given test txt is a file containing  ABCDEFGHIJKLMNOPQRSTUVWXYZ   cut -b19-20 test txt  gt  test1 txt   This will extract chars 19  amp  20  ST   while read -r  do   gt  x  REPLY  gt  done  lt  test1 txt echo  x ST

User · Answer

Without any sub-processes you can   shopt -s extglob front   input      a-zA-Z      digits   front     a-zA-Z       A very small variant of this will also work in ksh93

User · Answer

If x is constant  the following parameter expansion performs substring extraction   b   a 12 5    where 12 is the offset  zero-based  and 5 is the length  If the underscores around the digits are the only ones in the input  you can strip off the prefix and suffix  respectively  in two steps   tmp   a         remove prefix ending in     b   tmp         remove suffix starting with       If there are other underscores  it s probably feasible anyway  albeit more tricky   If anyone knows how to perform both expansions in a single expression  I d like to know too   Both solutions presented are pure bash  with no process spawning involved  hence very fast

User · Answer

There s also the bash builtin  expr  command     INPUT  someletters 12345 moreleters ext    SUBSTRING  expr match   INPUT           digit               echo  SUBSTRING

User · Answer

similar to substr  abcdefg   2-1  3  in php   echo  abcdefg  tail -c  2 head -c 3

User · Answer

Use cut   echo  someletters 12345 moreleters ext    cut -d    -f 2   More generic   INPUT  someletters 12345 moreleters ext  SUBSTRING   echo  INPUT  cut -d    -f 2  echo  SUBSTRING

User · Answer

I love sed s capability to deal with regex groups    gt  var  someletters 12345 moreletters ext   gt  digits    echo  var   sed  s       0-9         1 p  -n    gt  echo  digits 12345   A slightly more general option would be not to assume that you have an underscore   marking the start of your digits sequence  hence for instance stripping off all non-numbers you get before your sequence  s   0-9      0-9         1 p      gt  man sed   grep s regexp replacement -A 2 s regexp replacement      Attempt to match regexp against the pattern space   If successful  replace that portion matched with replacement   The replacement may contain the special  character   amp   to     refer to that portion of the pattern space which matched  and the special escapes  1 through  9 to refer to the corresponding matching sub-expressions in the regexp      More on this  in case you re not too confident with regexps    s is for  s ubstitute  0-9   matches 1  digits  1 links to the group n 1 of the regex output  group 0 is the whole match  group 1 is the match within parentheses in this case  p flag is for  p rinting   All escapes   are there to make sed s regexp processing work

User · Answer

shell cut - print specific range of characters or given part from a string  method1  using bash  str 2020-08-08T07 40 00 000Z  echo   str 11 8    method2  using cut  str 2020-08-08T07 40 00 000Z  cut -c12-19  lt  lt  lt   str   method3  when working with awk  str 2020-08-08T07 40 00 000Z  awk   time gensub    11    8       quot   1 quot   quot g quot   1   print time    lt  lt  lt   str

[string] Extract substring in Bash

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