echo + append string + linux

Question

please advice how it can be - ( this action was on linux machine )

why the string - "append" that I add with echo is after the line "spb_IP=172.17.100.122"

and not under the line - "spb_IP=172.17.100.122" ????

more file

 spa_IP=172.17.100.121
 spb_IP=172.17.100.122

echo "append" >> file

more file

 spa_IP=172.17.100.121
 spb_IP=172.17.100.122append this

echo -e "\nappend" >> file – InternetSeriousBusiness Sep 03 '12 at 14:51 — InternetSeriousBusiness, Sep 03 '12 at 14:51

user9517 · Accepted Answer · 2012-09-03T15:08:14.740

This will be because the file does not end in a \n.

hexdump -C file
00000000  73 70 61 5f 49 50 3d 31  37 32 2e 31 37 2e 31 30  |spa_IP=172.17.10|
00000010  30 2e 31 32 31 0a 73 70  61 5f 49 50 3d 31 37 32  |0.121.spa_IP=172|
00000020  2e 31 37 2e 31 30 30 2e  31 32 32                 |.17.100.122|

Note the file ends in 0x32 which is ASCII for 2

When you append to it it becomes

hexdump -C file
00000000  73 70 61 5f 49 50 3d 31  37 32 2e 31 37 2e 31 30  |spa_IP=172.17.10|
00000010  30 2e 31 32 31 0a 73 70  61 5f 49 50 3d 31 37 32  |0.121.spa_IP=172|
00000020  2e 31 37 2e 31 30 30 2e  31 32 32 61 70 70 65 6e  |.17.100.122appen|
00000030  64 0a

Note that as you have observed the 122 runs straight into the append 122append

To fix your 'problem' you need to

echo -e "\nappend"

to add the missing \n.

hexdump -C file
00000000  73 70 61 5f 49 50 3d 31  37 32 2e 31 37 2e 31 30  |spa_IP=172.17.10|
00000010  30 2e 31 32 31 0a 73 70  61 5f 49 50 3d 31 37 32  |0.121.spa_IP=172|
00000020  2e 31 37 2e 31 30 30 2e  31 32 32 0a 61 70 70 65  |.17.100.122.appe|
00000030  6e 64 0a                                          |nd.|

Now there is a . between the 122 and the append which represents the 0x0a (ASCII line Feed) character.

echo + append string + linux

1 Answers1