Problems encountered in office--

1.sed Special characters encountered

sed Pattern separator

up to now , We have only used one   Separator , That's it   The backslash （/）.

Suppose we need to use sed Enter... In the source  /bin/sed  Replace with  /home/yufei/bin/sed

because  /  Is the pattern separator , We have to escape it , namely  \/.

echo "/bin/sed" | sed 's/\/bin\/sed/\/home\/yufei\/bin\/sed/'

A vertical bar |

A vertical bar （|）  Should be   The backslash （/）  The most used delimiter outside .

Vertical lines can significantly improve sed Readability of pattern statements .

For example, the order above , We use a vertical bar as a separator , Can be rewritten as

echo "/bin/sed" | sed 's|/bin/sed|/home/yufei/bin/sed|'

2. The last line reads

tail -n 1 tt.txt

I will get One Blank line . In my case , I want to get bonjour.

use Awk：

awk '/./{ line=$0} END{print line}' tt.txt

3. Space split string

awk -F【 keyword 】 '{print $n}'

match_name=`echo "$match_Array" | awk -F ":"  '{print $1}' `