grep a tab in UNIX

Question

How do I grep tab   t  in files on the Unix platform

User · Answer

The answer is simpler  Write your grep and within the quote type the tab key  it works well at least in ksh  grep

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From this answer on Ask Ubuntu      Tell grep to use the regular expressions as defined by Perl  Perl has    t as tab    grep -P   t   lt file name gt        Use the literal tab character   grep   V lt tab gt    lt filename gt        Use printf to print a tab character for you   grep    printf   t     lt filename gt

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This works well for AIX  I am searching for lines containing JOINED lt  t gt ACTIVE  voradmin cluster status   grep  JOINED   t ACTIVE   vorudb201   1       MEMBER g  JOINED        ACTIVE  vorucaf01   2       SECONDARY JOINED        ACTIVE

User · Answer

There are basically two ways to address it     Recommended  Use regular expression syntax supported by grep 1   Modern grep 1  supports two forms of POSIX 1003 2 regex syntax  basic  obsolete  REs  and modern REs  Syntax is described in details on re format 7  and regex 7  man pages which are part of BSD and Linux systems respectively  The GNU grep 1  also supports Perl-compatible REs as provided by the pcre 3  library    In regex language the tab symbol is usually encoded by  t atom  The atom is supported by BSD extended regular expressions  egrep  grep -E on BSD compatible system   as well as Perl-compatible REs  pcregrep  GNU grep -P    Both basic regular expressions and Linux extended REs apparently have no support for the  t  Please consult UNIX utility man page to know which regex language it supports  hence the difference between sed 1   awk 1   and pcregrep 1  regular expressions    Therefore  on Linux     grep -P   t  FILE       On BSD alike system     egrep   t  FILE       grep -E   t  FILE      Pass the tab character into pattern  This is straightforward when you edit a script file     no tabs for Python please  grep -q         py  amp  amp  exit 1   However  when working in an interactive shell you may need to rely on shell and terminal capabilities to type the proper symbol into the line  On most terminals this can be done through Ctrl V key combination which instructs terminal to treat the next input character literally  the V is for  verbatim       grep   lt Ctrl gt   lt V gt  lt TAB gt   FILE       Some shells may offer advanced support for command typesetting  Such  in bash 1  words of the form   string  are treated specially   bash  grep    t  FILE       Please note though  while being nice in a command line this may produce compatibility issues when the script will be moved to another platform  Also  be careful with quotes when using the specials  please consult bash 1  for details   For Bourne shell  and not only  the same behaviour may be emulated using command substitution augmented by printf 1  to construct proper regex     grep   printf   t    FILE

User · Answer

The    t  notation given in other answers is shell-specific -- it seems to work in bash and zsh but is not universal   NOTE  The following is for the fish shell and does not work in bash   In the fish shell  one can use an unquoted  t  for example   grep  t foo txt   Or one can use the hex or unicode notations e g    grep  X09 foo txt grep  U0009 foo txt    these notations are useful for more esoteric characters   Since these values must be unquoted  one can combine quoted and unquoted values by concatenation   grep  foo  t bar

User · Answer

On ksh I used   grep    I   testfile

User · Answer

Using the  sed-as-grep  method  but replacing the tabs with a visible character of personal preference is my favourite method  as it clearly shows both which files contain the requested info  and also where it is placed within lines   sed -n  s  t          g  file name   If you wish to make use of line file info  or other grep options  but also want to see the visible replacement for the tab character  you can achieve this by  grep - options  -P   t  file name   sed  s  t          g    As an example     echo  A tB nfoo tbar   gt  test   grep -inH -P   t  test   sed  s  t          g  test 1 A    B test 2 foo    bar   EDIT  Obviously the above is only useful for viewing file contents to locate tabs --- if the objective is to handle tabs as part of a larger scripting session  this doesn t serve any useful purpose

User · Answer

The trick is to use   sign before single quotes  It also works for cut and other tools   grep    t  sample txt

User · Answer

Look for blank spaces many times    space       grep    space            Will find something like this    the tab      These are single quotations      and not double      This is how you make concatenation in grep   -

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These alternative binary identification methods are totally functional  And  I really like the one s using awk  as I couldn t quite remember the syntaxic use with single binary chars  However  it should also be possible to assign a shell variable a value in a POSIX portable fashion  i e  TAB echo       tr   100    011    and then employ it from there everywhere  in a POSIX portable fashion  as well  i e grep   TAB  filename   While this solution works well with TAB  it will also work well other binary chars  when another desired binary value is used in the assignment  instead of the value for the TAB character to  tr

User · Answer

You can type  grep  t foo or   grep   t  foo   to search for the tab character in the file foo   You can probably also do other escape codes  though I ve only tested  n   Although it s rather time-consuming  and unclear why you would want to  in zsh you can also type the tab character  back to the begin  grep and enclose the tab with quotes

User · Answer

grep    printf   t    worked for me on Mac OS X

User · Answer

One way is  this is with Bash   grep -P   t    -P turns on Perl regular expressions so  t will work   As user unwind says  it may be specific to GNU grep  The alternative is to literally insert a tab in there if the shell  editor or terminal will allow it

User · Answer

A good choice is to use  sed as grep   as explained in this classical sed tutorial    sed -n  s pattern  amp  p  file   Examples  works in bash  sh  ksh  csh            cat testfile 12 3 1 4 abc xa      c         a       c 2 1 23          sed -n  s  t  amp  p  testfile  xa      c         a       c 2          sed -n  s  ta t  amp  p  testfile         a       c 2

User · Answer

This is not exactly what you are looking for  but might work in your case  grep     blank       Equivalent to  grep -P     t     So it will find Space and Tab    sect  Character classes  Note  it is not advertised in my man grep  but still works     man grep   grep blank   wc       0       0       0

User · Answer

use gawk  set the field delimiter to tab   t  and check for number of fields  If more than 1  then there is are tabs  awk -F  t   NF gt 1  file

User · Answer

Use echo to insert the tab for you grep    echo -e   t

User · Answer

You might want to use grep    echo -e   t     Only requirement is echo to be capable of interpretation of backslash escapes

User · Answer

If using GNU grep  you can use the Perl-style regexp   grep -P   t

User · Answer

I never managed to make the   t  metacharacter work with grep  However I found two alternate solutions    Using  lt Ctrl-V gt   lt TAB gt   hitting Ctrl-V then typing tab  Using awk  foo   awk    t

User · Answer

Another way of inserting the tab literally inside the expression is using the lesser-known    t  quotation in Bash   grep   foo tbar           matches eg   foo lt tab gt bar     Note that if you re matching for fixed strings you can use this with  -F  mode    Sometimes using variables can make the notation a bit more readable and manageable   tab    t                   tab   printf   t    in POSIX id     digit       name     alpha       alnum   -    grep   name tab id        matches eg   bob2 lt tab gt 323

User · Answer

1 way  that works in ksh  dash  etc  use printf to insert TAB   grep    printf  BEGIN tEND    testfile txt

[unix] grep a tab in UNIX

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