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
– Jonathan Leffler, Commented Dec 20, 2014 at 9:23
thx, but speed is not really inportent for this task, just want it to do the right job :) — JohnnyF
– JohnnyF, Commented Dec 20, 2014 at 9:25

johnsyweb · Accepted Answer · 2014-12-20 09:25:32Z

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, 2014 at 9:25

answered Dec 20, 2014 at 9:19

johnsyweb

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3 Comments

JohnnyF Over a year ago

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 :)

johnsyweb Over a year ago

I was still editing my answer when you posted your follow-up :-)

JohnnyF Over a year ago

Dude, you really saved me, broke my head around, well thx a lot

Community · Accepted Answer · 2017-04-13 12:36:27Z

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, 2017 at 12:36

CommunityBot

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answered Dec 20, 2014 at 9:19

abelenky

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1 Comment

Jonathan Leffler Over a year ago

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 · Accepted Answer · 2014-12-20 10:34:22Z

-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, 2014 at 10:34

Jonathan Leffler

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answered Dec 20, 2014 at 9:35

armnotstrong

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2 Comments

PM 2Ring Over a year ago

Please don't encourage people to parse the output of ls

armnotstrong Over a year ago

thanks, accept that downvote, but life is dangerous anyway :)

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