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Top Forums Shell Programming and Scripting How to read a file starting at certain line number? Post 302950856 by rbatte1 on Wednesday 29th of July 2015 12:01:11 PM
Old 07-29-2015
It depends what you mean by "...read a file line by line from a certain line number."

The command tail with appropriate options might give you what you want. Can you elaborate on the requirement? Perhaps something like:-
Code:
tail +$lineNumber file

You can pass this into a loop line this:-
Code:
tail +$lineNumber file | while read line
do
    ..... # Whatever you need
done

You can make it more elaborate if you have multiple fields and/or field separators, so if it was colon separated : and you want to read five fields, you can:-
Code:
tail +$lineNumber file | while IFS=: read f1 f2 f3 f4 f5 
do
    ..... # Whatever you need
done



However, if you are just after a single line, you could use:-
Code:
sed -n${lineNumber}p file

Beware that this will read a single line and is therefore very IO intensive if you want to read multiple time from a file working down it.



I hope that these structures help. Can you explain a little more about the requirements?

Robin
 

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IRSEND(1)								FSF								 IRSEND(1)

NAME
irsend - basic LIRC program to send infra-red commands SYNOPSIS
irsend [options] DIRECTIVE REMOTE CODE [CODE...] DESCRIPTION
Asks the lircd daemon to send one or more CIR (Consumer Infra-Red) commands. This is intended for remote control of electronic devices such as TV boxes, HiFi sets, etc. DIRECTIVE can be: SEND_ONCE - send CODE [CODE ...] once SEND_START - start repeating CODE SEND_STOP - stop repeating CODE LIST - list configured remote items SET_TRANSMITTERS - set transmitters NUM [NUM ...] SIMULATE - simulate IR event REMOTE is the name of a remote, as described in the lircd configuration file. CODE is the name of a remote control key of REMOTE, as it appears in the lircd configuration file. NUM is the transmitter number of the hardware device. For the LIST DIRECTIVE, REMOTE and/or CODE can be empty: LIST "" "" - list all configured remote names LIST REMOTE "" - list all codes of REMOTE LIST REMOTE CODE - list only CODE of REMOTE The SIMULATE command only works if it has been explicitly enabled in lircd. -h --help display usage summary -v --version display version -d --device use given lircd socket [/var/run/lirc/lircd] -a --address=host[:port] connect to lircd at this address -# --count=n send command n times EXAMPLES
irsend LIST DenonTuner "" irsend SEND_ONCE DenonTuner PROG-SCAN irsend SEND_ONCE OnkyoAmpli VOL-UP VOL-UP VOL-UP VOL-UP irsend SEND_START OnkyoAmpli VOL-DOWN ; sleep 3 irsend SEND_STOP OnkyoAmpli VOL-DOWN irsend SET_TRANSMITTERS 1 irsend SET_TRANSMITTERS 1 3 4 irsend SIMULATE "0000000000000476 00 OK TECHNISAT_ST3004S" FILES
/etc/lirc/lircd.conf Default lircd configuration file. It should contain all the remotes, their infra-red codes and the corresponding timing and wave- form details. DIAGNOSTICS
If lircd is not running (or /var/run/lirc/lircd lacks write permissions) irsend aborts with the following diagnostics: "irsend: could not connect to socket" "irsend: Connection refused" (or "Permission denied"). SEE ALSO
The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory. lircd(8), mode2(1), smode2(1), xmode2(1), irrecord(1), irw(1), http://www.lirc.org. irsend 0.8.7pre1 May 2010 IRSEND(1)
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