Error in bash script - assign value to variable

Question

I am trying to make a small script that will give me the File names without the $2 first and $3 last names in a $1 directory

I have this code

#!/bin/bash
TOTFILES=find "$1" -maxdepth 1 -type f -exec basename {} ';' | wc -l
find "$1" -maxdepth 1 -type f -exec basename {} ';' | sort |
    head -n (( TOTFILES-$3 )) | tail -n (( TOTFILES-$3-$2 ))

My main problem is that I can't assign TOTFILES with the output of that long line.

I think if I can get that value assigned, it will work (hopefully) :)

PS: I don't know if I used

(( TOTFILES-$3 ))

right, to get the value.

Thanks for the fast answer. Now I get a new problem; I guess (( )) is not the right way to get number

./middleFiles: line 5: syntax error near unexpected token `('
./middleFiles: line 5: `find "$1" -maxdepth 1 -type f -exec basename {} ';' | sort | head -n (( TOTFILES-$3 ))  | tail -n (( TOTFILES-$3-$2 ))'

Note that the `exec basename` only slows things down unless you think directory names might contain newlines. Otherwise, you could be just as accurate with `-print` instead of `-exec`. — Jonathan Leffler, Dec 20 '14 at 09:23
thx, but speed is not really inportent for this task, just want it to do the right job :) — JohnnyF, Dec 20 '14 at 09:25

Johnsyweb · Accepted Answer · 2014-12-20T09:25:32.550

3

Command substitution assigns the output of a command:

TOTFILES=$(find "$1" -maxdepth 1 -type f -exec basename {} ';' | wc -l)

Arithmetic expansion will get you the argument to head and tail:

head -n $(( $TOTFILES - $3 ))

edited Dec 20 '14 at 09:25

answered Dec 20 '14 at 09:19

Johnsyweb

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exelent, but i have a follow up question ( i addd the question) i will be more then happy if you will be able to help me :) – JohnnyF Dec 20 '14 at 09:24
I was still editing my answer when you posted your follow-up :-) – Johnsyweb Dec 20 '14 at 09:26
Dude, you really saved me, broke my head around, well thx a lot – JohnnyF Dec 20 '14 at 09:29

score 0 · Answer 2 · edited Apr 13 '17 at 12:36

0

I believe you need backticks around the expression you want evaluated.

TOTFILES=`find "$1" -maxdepth 1 -type f -exec basename {} ';' | wc -l`

See this answer for details.

edited Apr 13 '17 at 12:36

Community

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answered Dec 20 '14 at 09:19

abelenky

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Modern style is to use `$(…)` in preference to backticks (` … `), and not just because it is hell getting backticks to appear in comments under Markdown. – Jonathan Leffler Dec 20 '14 at 09:22

score -2 · Answer 3 · edited Dec 20 '14 at 10:34

-2

I think best way is to assign filenames to an array. According to your code, you just want depth = 1 so simple ls trick will do the job

#!/bin/bash

TOTFILES=($(ls -p $1 | grep -v / | sort -n)

# and you can use the array like this
for file in ${TOTFILES[*]};do 
    echo $file;
done
# leave you to get a subset of the ${ToTFILES}
# refer to http://stackoverflow.com/questions/1335815/how-to-slice-an-array-in-bash

edited Dec 20 '14 at 10:34

Jonathan Leffler

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answered Dec 20 '14 at 09:35

armnotstrong

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Please don't encourage people to [parse the output of `ls`](http://mywiki.wooledge.org/ParsingLs) – PM 2Ring Dec 20 '14 at 09:55
thanks, accept that downvote, but life is dangerous anyway :) – armnotstrong Dec 20 '14 at 10:18

Error in bash script - assign value to variable

3 Answers3