[SOLVED] multi-line output from a bash script using echo and tr

Leo Simon · 08-13-2012, 01:05 PM

I want to do an ls -c1 from within a bash script, and output the result with one line per entry.

The command below returns a single very long line

#!/bin/bash
files=`ls -c1 *.help`
echo $files

The command below works fine from the command line (in tcsh)

echo `ls -c1 *.help` | tr "[:space:]" "\n"

But when I put it in a script (with any kind of shell) it returns just the first entry in $files

#!/bin/bash
files=`ls -c1 *.help` | tr "[:space:]" "\n"
echo $files

Any help would be most appreciated

lithos · 08-13-2012, 02:28 PM

Hi,

It's simple, you're missing " (double quotes) around the variable you're echo-ing

Code:

#!/bin/bash
files=$(ls -c1 *.help | tr "[:space:]" "\n")
echo "$files"

and use the $(command) syntax instead of `command` (backtick).

YankeePride13 · 08-13-2012, 02:33 PM

Try putting it in a loop:

for filename in `ls -c1 *.help`; do
echo "$filename"
done

trey85stang · 08-13-2012, 02:54 PM

Quote:

Originally Posted by YankeePride13

Try putting it in a loop:

for filename in `ls -c1 *.help`; do
echo "$filename"
done

bash can read from the file system already.

Code:

for f in *.help
do
  echo $f
done

Leo Simon · 08-13-2012, 02:58 PM

For your quick responses. They all work, but I liked lithos's solution the best. It's amazing how many times double quotes fixes things, and more amazing (i.e., pathetic) that I never remember this

Valery Reznic · 08-14-2012, 08:01 AM

Quote:

Originally Posted by Leo Simon

For your quick responses. They all work, but I liked lithos's solution the best. It's amazing how many times double quotes fixes things, and more amazing (i.e., pathetic) that I never remember this

If sorting by ctime is not that important for you, I think trey85stang's solution is better:
1. It avoid quite redundant invocation of external programs
2. It will works even if filenames have spaces. lithos's solution will break parts of such filenames to separate lines.

lithos · 08-14-2012, 11:43 AM

Quote:

Originally Posted by Valery Reznic

If sorting by ctime is not that important for you, I think trey85stang's solution is better:
1. It avoid quite redundant invocation of external programs
2. It will works even if filenames have spaces. lithos's solution will break parts of such filenames to separate lines.

Good point!
I was merely correcting Leo's line "echo `ls -c1 *.help` | tr "[:space:]" "\n""
to make echo print out with lines.

Valery Reznic · 08-15-2012, 02:05 AM

Quote:

Originally Posted by lithos

Good point!
I was merely correcting Leo's line "echo `ls -c1 *.help` | tr "[:space:]" "\n""
to make echo print out with lines.

Sure, there is a great value in explaining where error is and why some code doesn't work as expected