Basic shell text processing tools

grep tool

grep is a line filtering tool; filtering based on keywords

Syntax and option
syntax:

 grep [选项] “关键字” 文件名

Common options:

• -i is not case sensitive
• -v does not include reverse selection
• -w search by word (exact match)
• -o print matching keywords
• -c count the number of matches
• -n display line number
• -r traverse the directory layer by layer to find
• -A matches the following lines
• -B matches the first few lines of the line
• -C matches a few lines before and after the line
• -l only lists matching file names
• -L lists unmatched file names
• -e Use regular matching
• -E Use extended regular matching
• ^key starts with a keyword
• key$ ends with the keyword
• ^$ matches blank lines

for example:

# 忽略大小写匹配root的行
  grep -i 'root' passwd
# 精准匹配单词
  grep -w 'ftp' passwd
# 以#开头的行
  grep ^# passwd
# 不以#开头的行
  grep -v ^# passwd
# 以bash结尾的行
  grep bash$ passwd
# 打印空行行号
  grep -n ^$ passwd

cut tool

cut is a column interception tool