Formatting Numerics With Bash

A repeated need I've encountered is a need to format a numeric with leading zeros, similar to the common form used in C.  Typically, I take a over-complicated approach of comparing the number to >100 or >10 and pre-pending leading zeros.

After investigating alternative approaches with good 'ole Google, the better approach is shown below;

$ cat /tmp/go 
#!/bin/bash

for i in `seq 100`; do
  N=$(printf %03d $i)
  echo $N
done

Cheers.

Piping to Tcl Script

Ok, maybe I've lived up to my name. I may very well be the fat slow
kid.

I struggled for some time trying to figure out how to pipe input to a Tcl script and immediately ventured off on a quest for opening a pipe (|) file descriptor. In actuality however, since I wanted to pipe input into the tcl script my needs are met by:

#!/usr/bin/tclsh
while { [gets stdin line] >= 0 } {
puts "got '$line'"
}

so

$ ls | ./tclPipe

results in

got 'Desktop'
got 'IM'
got 'ImagingManager.tar.gz'
got 'ISC'
got 'tclPipe'

My quest however also recovered if the input command is fixed:

#!/usr/bin/tclsh

set fp [open "|ls" r]
while { [gets $fp line] >= 0 } {
  puts "got $line"
}

would surfice.