Why history command doesn't work in shell

Asked Apr 19 '17 at 03:41

Active Jul 06 '23 at 00:54

Viewed 1,970 times

I'm working on Mac OS Sierra Shell.
Here is an example:

#!/bin/bash
contenu=`df`
echo ${contenu}

When I execute this shell, I can see the result of df.

However, when I try to print the first line of history, I can just see an empty line.

#!/bin/bash
contenu=`history | head -1`
echo ${contenu}

I've also executed the same command on the terminal and it worked very well.

user$ history | head -1

When I execute the command above, I can see what I'm waiting for. For example:

   161 ls -l

edited May 08 '17 at 09:05

Martijn Pieters

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asked Apr 19 '17 at 03:41

Yves

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Whats the out of `history | head -1` when you run it interactively? – heemayl Apr 19 '17 at 03:43
@heemayl well, I can get what I want, meaning that the first line of `history` is shown. – Yves Apr 19 '17 at 03:44
It works perfectly for me. – bansi Apr 19 '17 at 03:51
Are you running those two commands in the shell, or in a separate script? The latter will start a subshell/session (whatever you like to call it), with an empty history. – Apr 19 '17 at 03:51
@bansi I really dont know what to say... Is it because I used OSX instead of Linux? – Yves Apr 19 '17 at 03:52
1

See https://unix.stackexchange.com/questions/5684/history-command-inside-bash-script – Apr 19 '17 at 03:52
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If you repeatedly run `echo ${contenu}`, do you get empty line each time? If not, perhaps your `~/.bash_history` file had an empty line for the line you were trying to fetch with `echo ${contenu}`. I am OSX and have no issue with either running `history | head -1` or `echo ${contenu}` – zedfoxus Apr 19 '17 at 03:53
For the record, there is no "Mac OS Sierra Shell.". That will be bash by default. – Apr 19 '17 at 03:54
@zedfoxus yeah, I repeatedly run `echo ${contenu}` and I get many empty lines... – Yves Apr 19 '17 at 03:55
don't know, tested with linux and it works. – bansi Apr 19 '17 at 03:55
try a different line or just try `history | head` – bansi Apr 19 '17 at 03:57
@bansi still empty..... – Yves Apr 19 '17 at 04:00
What's the output of `history | head -10`? What's the output of `echo $SHELL`? – zedfoxus Apr 19 '17 at 04:00
@Evert oooh, it works! Thanks. Plz redirect my question or answer it. – Yves Apr 19 '17 at 04:05
@Yuhui very nice. What was the issue and how did you fix it? – zedfoxus Apr 19 '17 at 04:14
@zedfoxus https://unix.stackexchange.com/questions/5684/history-command-inside-bash-script – Yves Apr 19 '17 at 04:24
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@Yuhui That link has many answers. Which answer helped? Was it just `set -o history`? – zedfoxus Apr 19 '17 at 04:26
@zedfoxus yes. Well it is not the real-time history but at least, I can get history. – Yves Apr 19 '17 at 05:17
@Yuhui Thank you for sharing what worked best for you. Much appreciated. – zedfoxus Apr 19 '17 at 05:21

Why history command doesn't work in shell

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