[Solved] Alias in ash - syntax or limitation issue

Installing and Using OpenWrt
1

Hello:

As you may have seen in previous posts, I'm running OpenWRT in a NAS (WD-MBL).

Now, I'm putting together a set of aliases to make maintenance easier via the command line.

These work as expected:

alias shutdown='sync && wait && sudo hdparm -Y /dev/sda && wait && sudo halt'

Shuts down the NAS gracefully.

daemon='sudo /etc/init.d/rsyncd status'

Tells me the rsync daemon's status.

drivechk='sudo dmesg | grep -i ext4-fs | grep -i sda'

Alerts me to filesystem issues caused by a bad shutdown requiring e2fsck.

tempchk='sudo smartctl -d ata -A /dev/sda | grep Temperature | cut -c 5-8,87-89'

Tells me the drive temperature.

But there is one which I have not been able to get to work:

fschk='df -h | grep -vE '^Filesystem|/dev/root|tmpfs'| awk '{ print $5 " " $1}'

The stanza run from the command line works as expected:

~$ df -h | grep -vE '^Filesystem|/dev/root|tmpfs'| awk '{ print $5 " " $1}'
53% /dev/sda1
37% /dev/sda3
~$

If I add this to the /etc/profile.d/custom.sh file, log out and log in again I get this on the terminal:

~$ ssh user@192.168.1.3
--- snip ---
BusyBox v1.33.2 (2022-02-16 20:29:10 UTC) built-in shell (ash)

alias:  }' not found

~$

Something seems to be wrong.
If I then run the alias I get this:

~$ fschk
>

Makes sense as on login the system prints out something that implies that something is wrong with the alias.

If I query the alias list from the command line, I see that the one I added is shown differently in the printout:

~$ alias
--- snip ---
fschk='df -h|grep -vE '"'"'^/dev/root|tmpfs'"'"'|awk '"'"'{print  '
--- snip ---
:~$

But not in the /etc/profile.d/custom.sh file where it remains as I typed it:

~$ cat /etc/profile.d/custom.sh
--- snip ---
alias fschk="df -h|grep -vE '^/dev/root|tmpfs'|awk '{print $5 " " $1}'"
--- snip ---
~$

It seems that ash has a different/reduced version of alias but I cannot figure this one out.

ie: if it works as expected from the command line, why doesn't it work as an alias?

Any pointers will be greatly appreciated.

Thanks in advance.

Best,

PCL

3

The following appears to work:
alias fschk="(df -h | grep -vE '^Filesystem|/dev/root|tmpfs'|awk '{print \$5 \" \" \$1}')"

I suppose Busybox's ash is a tad buggy or something, but I had to enclose the whole command-line in parentheses to get it to work.

2 Likes
4

Hello:

Indeed it does. 8^ )

~$ fschk
53% /dev/sda1
37% /dev/sda3
~$

Can't say.
I did not know it existed before using OpenWRT.

Thank you very much for taking the time to see what was up.
Now on to the script.

Best,

PCL

5

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