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Ksh save command result to variable

I want to save the result of a command to a variable in my shell script. I can't seem to get it to work. I want the latest file to be found in the folder.

PRODUCT= 'ls -t /some/dir/file* | head -1 | xargs -n1 basename'

he does not work

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5 answers


you have two options: $

or backsticks `

.

1) x=$(ls -t /some/dir/file* | head -1 | xargs -n1 basename)

or



2) x=`ls -t /some/dir/file* | head -1 | xargs -n1 basename` 

echo $x

Edit: Removing unnecessary parenthesis for (2).

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The problem you are running into is that the command must be surrounded by back ticks, not single quotes. This is called "Command Substitution".

Bash allows $()

for command substitution, but this is not available in all shells. I don't know if this is available at KSH; if so, it may not be available in all versions.

If the syntax $()

is available in your version of ksh, you must use it; easier to read (backticks are too easy to mix with single quotes); back-ticks are also hard to nest.

This only addresses one of the problems with your command: it ls

returns directories as well as files, so if the last changed in the specified directory is a subdirectory, that's what you'll see.

If you only want to see files, I suggest using some version of the following (I am using Bash which supports variables by default, you may have to play around with the syntax $1

)



lastfile () 
{ 
    find ${1:-.} -maxdepth 1 -type f -printf "%T+ %p\n" | sort -n | tail -1 | sed 's/[^[:space:]]\+ //'
}

Searches a directory and extracts files from that directory. It formats all files as follows:

2012-08-29+16:21:40.0000000000 ./.sqlite_history
2013-01-14+08:52:14.0000000000 ./.davmail.properties
2012-04-04+16:16:40.0000000000 ./.DS_Store
2010-04-21+15:49:00.0000000000 ./.joe_state
2008-09-05+17:15:28.0000000000 ./.hplip.conf
2012-01-31+13:12:28.0000000000 ./.oneclick

sorts the list, takes the last line, and discards everything before the first space.

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You want $()

( preferred ) or backticks ('') (older style) than single quotes:

PRODUCT=$(ls -t /some/dir/file* | head -1 | xargs -n1 basename)

or

PRODUCT=`ls -t /some/dir/file* | head -1 | xargs -n1 basename`
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You need both quotes so that you keep the name even if it contains spaces, and also if you need more than 1 file, and "$ (..)" to run commands in the background

I believe you also need the "-1" option for ls, otherwise you may have multiple names per line (you only store one line, but there may be multiple files)

PRODUCT="$(ls -1t /some/dir/file* | head -1 | xargs -n1 basename)"

Don't put space around the "=" variable assignments (as I've seen on other solutions here), as it's not very compatible either.

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I would like to do something like:

Your version is fixed:

PRODUCT=$(ls -t /some/dir/file* | head -1 | xargs -n1 basename)

Or more simply:

PRODUCT=$(cd /some/dir && ls -1t file* | head -1)
  • go to catalog
  • list one filename per line and sort by time / date
  • grab the first line
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