我正在尝试编写一个bash脚本，但我没有在终端中显示结果

Question

i'm trying to display the 3rd to the 7th line from a file but i get nothing displayed in the terminal i'm using this command :

head -n 7 /etc/passwd | tail -n +3

i want the result be seen in the terminal .

Answer 1

You can try this way

head -n 7 /etc/passwd | tail -n 5

For example :

seq 20 | head -n 7 | tail -n 5

Output :

3
4
5
6
7

Explanation :

head -n 7       -- print the  first 7 lines ( so 1..7 printed)
tail -n 5       -- print last 5 lines ( so skipped first two lines 3..7 printed )

Answer 2

head -n 7 /etc/passwd | tail -n +3

Seems to do exactly what you want it to do for me. Have you verified the contents of /etc/passwd? If you do not have permission to read the file or it is empty you will get no output.

I would check other places in the script. Change the first line of your script to:

#!/bin/bash -v

to have it echo the commands so you can make sure what you think is being executed actually is.

Answer 3

What do you get than ? Show the file output, but choose another file ;)

It sometimes helps to just change commands, try with either HEAD or TAIL twice, to come to the same result.