Reading specific data from multiple files in Tcl - regex

Question

I am writing a TCL script to read multiple files and search them for a line containing certain word using regexp. I have been able to search for one thing from the files. But I need to modify the script to search for multiple things in a script print the items found in one file together in one line, then the items found from another file in 2nd line.
I have written this
foreach fileName [glob /home/kartik/tclprac/*/*] {
# puts " Directories present are: [file tail $fileName]"
set fp [open $fileName "r"]
while { [gets $fp data]>=0 } {
if {[regexp {set Date*} $data] | [regexp {set Channel* } $data] } {
#puts "file: [file dirname $fileName] data: $data"
set information "file: [file dirname $fileName] data: $data"
puts $information
set fp2 [open output.txt "a"]
puts $fp2 $information
}
}
}
Now i am getting output as:
file: /home/kartik/tclprac/wire_3 data: set Date 02/08/2021
file: /home/kartik/tclprac/wire_2 data: set Date 01/08/2021
file: /home/kartik/tclprac/wire_1 data: set Channel Disney
file: /home/kartik/tclprac/wire_1 data: set Date 31/07/2021
what i want is something like
file: /home/kartik/tclprac/wire_3 data: set Date 02/08/2021
file: /home/kartik/tclprac/wire_2 data: set Date 01/08/2021
file: /home/kartik/tclprac/wire_1 data: set Date 31/07/2021 set Channel Disney

Answer 1

It looks to me like you want to gather the results for a single file onto a single line, rather than printing out a line for each matching line (the traditional grep tool approach) with the per-line results being separated by spaces.
We can do this, but it gets a bit clearer if we split the code up into a couple of procedures (one for processing the contents of a single file, the other for the whole job).
proc processFileContents {name contents accumulatorChannel} {
set interesting [lmap line [split $contents "\n"] {
if {![regexp {set (?:Date|Channel) } $line]} {
# SKIP non-matching lines
continue
}
# Trim the matching lines
string trim $line
}]
# If we matched anything, print out
if {[llength $interesting]} {
set information "file: $name data: [join $interesting \n]"
puts $information
puts $accumulatorChannel $information
}
}
proc processFilesInDir {pattern accumulatorChannel} {
foreach fileName [glob -nocomplain -type f $pattern] {
set channel [open $fileName]
set contents [read $channel]
close $channel
processFileContents $fileName $contents $accumulatorChannel
}
}
set accum [open output.txt "a"]
processFilesInDir /home/kartik/tclprac/*/* $accum
close $accum
If you're using an older version of Tcl that doesn't have lmap (8.5 or before) then you can write that with foreach (as lmap is really just a collecting form of foreach; the only difference is that lmap uses a hidden temporary variable to do the accumulating):
proc processFileContents {name contents accumulatorChannel} {
set interesting {}
foreach line [split $contents "\n"] {
if {![regexp {set (?:Date|Channel) } $line]} {
# SKIP non-matching lines
continue
}
# Trim the matching lines
lappend interesting [string trim $line]
}
# If we matched anything, print out
if {[llength $interesting]} {
set information "file: $name data: [join $interesting \n]"
puts $information
puts $accumulatorChannel $information
}
}