如何在Unix平台上的文件中grep标签(\t) ?


当前回答

基本上有两种解决方法:

(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 && 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 '<Ctrl>+<V><TAB>' 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 ...

其他回答

你可能想使用grep "$(echo -e '\t')"

唯一的要求是echo能够解释反斜杠转义。

我用ksh

grep "[^I]" testfile

如果使用GNU grep,你可以使用perl风格的regexp:

grep -P '\t' *

使用gawk,将字段分隔符设置为TAB (\t)并检查字段的数量。如果多于1,则有/有制表符

awk -F"\t" 'NF>1' file

诀窍是在单引号前使用$符号。它也适用于切割和其他工具。

grep $'\t' sample.txt