三大文本处理工具grep、sed及awk

[root@localhost tmp]# seq 10
1
2
3
4
5
6
7
8
9
10
[root@localhost tmp]# seq 10 | grep 5 -A 3　　#打印匹配的后指定行数
5
6
7
8
[root@localhost tmp]# seq 10 | grep 5 -B 3　　#打印匹配前指定行数
2
3
4
5
[root@localhost tmp]# seq 10 | grep 5 -C 3    #打印匹配前后指定行数
2
3
4
5
6
7
8

[root@cairui ~]# sed --help
Usage: sed [OPTION]... {script-only-if-no-other-script} [input-file]...

  -n, --quiet, --silent
                 suppress automatic printing of pattern space　　#取消自动打印模式空间
  -e script, --expression=script
                 add the script to the commands to be executed　　#添加“脚本”到程序的运行列表
  -f script-file, --file=script-file
                 add the contents of script-file to the commands to be executed　　#添加“脚本文件”到程序的运行列表
  --follow-symlinks
                 follow symlinks when processing in place; hard links
                 will still be broken.
  -i[SUFFIX], --in-place[=SUFFIX]
                 edit files in place (makes backup if extension supplied).
                 The default operation mode is to break symbolic and hard links.
                 This can be changed with --follow-symlinks and --copy.
  -c, --copy
                 use copy instead of rename when shuffling files in -i mode.
                 While this will avoid breaking links (symbolic or hard), the
                 resulting editing operation is not atomic.  This is rarely
                 the desired mode; --follow-symlinks is usually enough, and
                 it is both faster and more secure.
  -l N, --line-length=N
                 specify the desired line-wrap length for the `l' command
  --posix
                 disable all GNU extensions.
  -r, --regexp-extended
                 use extended regular expressions in the script.
  -s, --separate
                 consider files as separate rather than as a single continuous
                 long stream.
  -u, --unbuffered
                 load minimal amounts of data from the input files and flush
                 the output buffers more often
      --help     display this help and exit
      --version  output version information and exit

If no -e, --expression, -f, or --file option is given, then the first
non-option argument is taken as the sed script to interpret.  All
remaining arguments are names of input files; if no input files are
specified, then the standard input is read.

GNU sed home page: <http://www.gnu.org/software/sed/>.
General help using GNU software: <http://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-gnu-utils@gnu.org>.
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.

[root@cairui ~]# awk --help
Usage: awk [POSIX or GNU style options] -f progfile [--] file ...
Usage: awk [POSIX or GNU style options] [--] 'program' file ...
POSIX options:        GNU long options:
    -f progfile        --file=progfile
    -F fs            --field-separator=fs
    -v var=val        --assign=var=val
    -m[fr] val
    -O            --optimize
    -W compat        --compat
    -W copyleft        --copyleft
    -W copyright        --copyright
    -W dump-variables[=file]    --dump-variables[=file]
    -W exec=file        --exec=file
    -W gen-po        --gen-po
    -W help            --help
    -W lint[=fatal]        --lint[=fatal]
    -W lint-old        --lint-old
    -W non-decimal-data    --non-decimal-data
    -W profile[=file]    --profile[=file]
    -W posix        --posix
    -W re-interval        --re-interval
    -W source=program-text    --source=program-text
    -W traditional        --traditional
    -W usage        --usage
    -W use-lc-numeric    --use-lc-numeric
    -W version        --version

To report bugs, see node `Bugs' in `gawk.info', which is
section `Reporting Problems and Bugs' in the printed version.

gawk is a pattern scanning and processing language.
By default it reads standard input and writes standard output.

Examples:
    gawk '{ sum += $1 }; END { print sum }' file
    gawk -F: '{ print $1 }' /etc/passwd