I've defined a variable inside a shell script and I want to use it. For some reason, I cannot pass it into to command line that I need it in.
Here's my script which fails at the last lines
#! /usr//bin/tcsh -f
if ( $# != 2 ) then
echo "Usage: jump_sorter.sh <jump> <field to sort on>"
exit;
endif
set a = `cat $1 | tail -1` #prepares last row for check with loop
set b = $2 #this is the value last row will be checked for
set counter = 0
foreach i ($a)
if ($i == "$b") then
set bingo = $counter
echo "$bingo is the field to print from $a"
endif
set counter = `expr $counter + 1`
end
echo $bingo #this prints the correct value for using in the command below
cat $1 | awk '{print($bingo)}' | sort | uniq -c | sort -nr #but this doesn't work.
#when I use $9 instead of $bingo, it does work.
How can I pass $bingo into the final line correctly, please?
Update: following the accepted answer from Martin Tournoij, the correct way to handle the "$" sign in the command is:
cat $1 | awk "{print("\$"$bingo)}" | sort | uniq -c | sort -nr
The reason it doesn't work is because variables are only substituted inside double quotes ("
), not single quotes ('
), and you're using single quotes:
cat $1 | awk '{print($bingo)}' | sort | uniq -c | sort -nr
The following should work:
cat $1 | awk "{print($bingo)}" | sort | uniq -c | sort -nr
You also have an error here:
#! /usr//bin/tcsh -f
That should be:
#!/usr/bin/tcsh -f
Note that csh isn't usually recommended for scripting; it has many quirks and lacks some features like functions. Unless you really need to use csh, it's recommended to use a Bourne shell (/bin/sh
, bash, zsh) or a scripting language (Python, Ruby, etc.) instead.
There is needless use of cat in the first two examples. The file can be redirected back into awk without the use of cat. The processing of sort and uniq could most probably be done within awk also, which removes any inefficiencies associated with piping.
@RamanSailopal could you provide an example please?
awk "{print($bingo)}" $1
On modern systems this hardly makes a difference @RamanSailopal, not unless you're running it hundreds of time.