Running a piped unix command from a Tcl script

Question

I am trying to run the following:

exec tail CRON_GBOI_INC_AVG_COMPRESS_20140425_18* | grep -i "status of" | awk -F" " '{ print $NF }'

What it does is it tails the file, grep for the line containing the text status of, which will return a string and then return the last character in the string.

However, Tcl always throws the following error:

missing close-bracket or close-brace while compiling that line.

How can I change the code to do what I need to achieve? Is it at all possible with Tcl?

Donal Fellows · Accepted Answer · 2014-04-28 21:14:28Z

1

Tcl's syntax is not the shell's syntax. The conversion of that line would be:

exec tail {*}[glob CRON_GBOI_INC_AVG_COMPRESS_20140425_18*] | \
        grep -i "status of" | awk "-F " {{ print $NF }}

That's to say, the globbing is explicit, the double quotes are round whole words, and the single quotes are changed to braces. (It's also broken over 2 lines with a backslash-newline sequence for clarity.)

answered Apr 28, 2014 at 21:14

Donal Fellows

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1 Comment

czchlong Over a year ago

Unfortunately that isn't working for me. This is the error message I get

extra characters after close-brace while compiling "exec tail {*}[glob CRON_GBOI_INC_AVG_COMPRESS_20140425_18*] | grep -i "status of" | awk -F" " {{ print $NF }}..."

I also tried your syntax of awk "-F " which also doesn't work. `

ijembe · Accepted Answer · 2014-05-02 02:34:55Z

0

Sirs, As it happens, Tcl string handling may make this easier:-

set stringBack [exec tail [lindex $argv 0] | grep -i "[lindex $argv 1]" ]
set wanted [string index $stringBack end]
puts "stat chr is $wanted"

.

We run as, say,

./charget /path/to/file 'text hook we choose'

with file and text hook as parameters (quoting the text hook string for handoff to grep insensitive).

answered May 2, 2014 at 2:34

ijembe

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