mjhjmtu

I am trying to store a command in a variable, so that it can be run on a remote server later. The asterisk is being replaced with the folder names and is being stored in the variable. I need the command to be as it is with the asterisk fir later usage.

Script:

#!/bin/bash
cmd="ls -lrt /client/*/ver* /client/*/*/ver* | grep 299 | tail -1"
echo $cmd

Output:

./script.sh 
ls -lrt /client/folder299/version_1 /client/ifolder299/ifolder/version_a /client/ifolder300/ifolder1/version_b /client/ifolder301/ifolder2/version_c /client/ifolder302/ifolder3/version_d | grep 299 | tail -1

I tried searching around with no luck. Could someone help me with a way to store the command as it is?

The command is not evaluated and the string is stored as is in the variable. It's the globbing patterns that are expanded when you output the unquoted variable.

cmd="ls -lrt /client/*/ver* /client/*/*/ver* | grep 299 | tail -1"

This is safe and would set cmd to the literal string ls -lrt /client/*/ver* /client/*/*/ver* | grep 299 | tail -1. The difference between using double quotes and single quotes around the string doesn't matter in this case (but I would have used single quotes as this is a static string). It doesn't matter in the sense that there is no expansion of anything for the shell to do in the string. Had there been variables or command substitutions in the string, the shell would have expanded those, but there are none.

When you output the value of the variable using echo $cmd, the globbing patterns would be expanded (this is what happens), but the command would still not be run.

To stop the globbing patterns from being expanded, double quote the variable expansion as "$cmd". Personally, I would use

printf '%sn' "$cmd"

to print its value. See "Why is printf better than echo?" for why.

Related:

• How can we run a command stored in a variable?

Note also that since you're parsing the output of ls -l (which in itself is not safe), and then grepping for a number, you would pick that number up from anywhere in the ls -l output, for example in the size of a file.

I would advise that you rethink what the bigger picture issue is that you're trying to solve, and then that you ask a brand new question about that instead.

To find the most recently modified regular file out of a list of pathnames, you may do

unset newest
for pathname in /client/*/ver* /client/*/*/ver*; do
 if [ -f "$pathname" ] && [ "$pathname" -nt "$newest" ]; then
 newest=$pathname
 fi
done

This is assuming that the filename globbing patterns that you've mentioned expands to the names that you'd like to check. To additionally restrict this to only allow filenames containing the string 299:

unset newest
for pathname in /client/*/ver* /client/*/*/ver*; do
 if [[ "$pathname##*/" == *299* ]] &&
 [ -f "$pathname" ] && [ "$pathname" -nt "$newest" ]; then
 newest=$pathname
 fi
done

If the globbing patterns expand to directories that you need to look into recursively, then using bash:

shopt -s globstar
unset newest
for pathname in /client/*/ver*/** /client/*/*/ver*/**; do
 if [[ "$pathname##*/" == *299* ]] &&
 [ -f "$pathname" ] && [ "$pathname" -nt "$newest" ]; then
 newest=$pathname
 fi
done

Example of running this over SSH:

ssh user@host bash -s -O globstar <<'END_SCRIPT'
for pathname in /client/*/ver*/** /client/*/*/ver*/**; do
 if [[ "$pathname##*/" == *299* ]] &&
 [ -f "$pathname" ] && [ "$pathname" -nt "$newest" ]; then
 newest=$pathname
 fi
done
printf 'Newest file: %sn' "$newest"
END_SCRIPT

May be the option f :

$ touch /tmp/filetmp
$ c="ls /tmp/*"

$ set -f
$ echo $c
ls /tmp/*

$ set +f
$ echo $c
ls /tmp/filetmp

$ rm /tmp/filetmp
$ unset c

Under linux, usually by default the option is +f

Sorry for the above confusion.

The issue is resolved with providing the command directly in the following way.

ssh username@host "ls -lrt /client/*/ver* /client/*/*/ver* | grep $4 | tail -1" 

Use single quote while storing the commands into variable. Use double quotes while using in echo command.

$ cmd='ls -lrt /var/* /tmp/* /home/* | grep test | tail -1'
$ echo "$cmd"
ls -lrt /var/* /tmp/* /home/* | grep test | tail -1

Difference between single and double quotes