"Shell script to tail a file with unknown numbers"

Post #303038721 by apmcd47 on Thursday 12th of September 2019 06:52:30 AM

Assuming GNU tail you can either list lines from the end (--lines=1234) or from the beginning (--lines=+1234) of the file. Thus listing the full file could be done with
Code:
tail --lines=+1 myfile

In your script you could have a variable nlines which could contain the value 100000, 200000 or +1 and could be used thus:
Code:
tail --lines=$nlines $logfile

The best way to get the values into your script would be to use getopts as in
Code:
while getopts lhf name
do
   case $name in
   l) nlines=100000 ;;
   h) nlines=200000 ;;
   f) nlines=+1 ;;
   esac
done
shift $(( OPTIND - 1))

The log files could be added to the end of the argument list or with more option switches using getopts (use the bash help facility for more info).

Andrew
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Tcl_AllowExceptions(3tcl)				      Tcl Library Procedures					 Tcl_AllowExceptions(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME
Tcl_AllowExceptions - allow all exceptions in next script evaluation SYNOPSIS
#include <tcl.h> Tcl_AllowExceptions(interp) ARGUMENTS
Tcl_Interp *interp (in) Interpreter in which script will be evaluated. _________________________________________________________________ DESCRIPTION
If a script is evaluated at top-level (i.e. no other scripts are pending evaluation when the script is invoked), and if the script termi- nates with a completion code other than TCL_OK, TCL_ERROR or TCL_RETURN, then Tcl normally converts this into a TCL_ERROR return with an appropriate message. The particular script evaluation procedures of Tcl that act in the manner are Tcl_EvalObjEx, Tcl_EvalObjv, Tcl_Eval, Tcl_EvalEx, Tcl_GlobalEval, Tcl_GlobalEvalObj, Tcl_VarEval and Tcl_VarEvalVA. However, if Tcl_AllowExceptions is invoked immediately before calling one of those a procedures, then arbitrary completion codes are per- mitted from the script, and they are returned without modification. This is useful in cases where the caller can deal with exceptions such as TCL_BREAK or TCL_CONTINUE in a meaningful way. KEYWORDS
continue, break, exception, interpreter Tcl 7.4 Tcl_AllowExceptions(3tcl)

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