檔案內容的關鍵詞匹配

對於一個內容很多的檔案，如果需要查詢某個關鍵詞及其所在的位置，可以使用grep命令進行搜尋。grep命令是一個非常強大的文字處理命令，主要功能是根據關鍵詞對文字進行篩選，查詢匹配的關鍵詞並輸出位置，grep命令提供了許多選項，常用選項如下所示。

-a：不要忽略二進位制資料
-b：出現時查詢到的行號外，還匹配顯示字元所在的整個文件的位置
-c：顯示匹配關鍵詞的內容和行數合計
-e：指定關鍵詞，使用該選項可指定多個關鍵詞
-E：指定正則表示式
-i：查詢是不區分大小寫
-n：顯示匹配行的行號
-w：顯示和關鍵詞完全匹配的內容
-o：只輸出文件中匹配到的內容

接下來以.bashrc檔案為例進行演示grep命令的使用方法

#使用grep命令搜尋bashrc檔案中含有if的行
[email protected]:~$ grep if .bashrc
#check the window size after each command and, if necessary,
#set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
#uncomment for a colored prompt, if the terminal has the capability; turned
 

if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
if [ "$color_prompt" = yes ]; then
if [ -x /usr/bin/dircolors ]; then
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''
 
s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
if [ -f ~/.bash_aliases ]; then
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
  elif [ -f /etc/bash_completion ]; then

#使用-b選項，能夠輸出匹配關鍵詞的行號
[email protected]:~$ grep -b if .bashrc
544:# check the window size after each command and, if necessary,
957:# set variable identifying the chroot you work in (used in the prompt below)
1034:if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
1282:# uncomment for a colored prompt, if the terminal has the capability; turned
1515:if [ -n "$force_color_prompt" ]; then
1553:    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
1855:if [ "$color_prompt" = yes ]; then
2334:if [ -x /usr/bin/dircolors ]; then
2958:alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
3334:if [ -f ~/.bash_aliases ]; then
3460:# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
3558:if ! shopt -oq posix; then
3585:  if [ -f /usr/share/bash-completion/bash_completion ]; then
3695:  elif [ -f /etc/bash_completion ]; then

#使用-w選項進行全字匹配，即必須與制定關鍵詞完全匹配才可以搜尋到
#即使包含關鍵詞也不可以被匹配到
[email protected]:~$ grep -bw if .bashrc
544:# check the window size after each command and, if necessary,
1034:if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
1282:# uncomment for a colored prompt, if the terminal has the capability; turned
1515:if [ -n "$force_color_prompt" ]; then
1553:    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
1855:if [ "$color_prompt" = yes ]; then
2334:if [ -x /usr/bin/dircolors ]; then
3334:if [ -f ~/.bash_aliases ]; then
3460:# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
3558:if ! shopt -oq posix; then
3585:  if [ -f /usr/share/bash-completion/bash_completion ]; then

#使用-o選項能夠輸出匹配項的內容，而不是所在行的所有內容
[email protected]:~$ grep -bwo if .bashrc
592:if
1034:if
1316:if
1515:if
1557:if
1855:if
2334:if
3334:if
3468:if
3558:if
3587:if