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596
Votes: 7
✅ Solution
Tags:
command-line
bash
yad
Link:
🔍 See Original Answer on Ask Ubuntu ⧉ 🔗
URL:
https://askubuntu.com/q/1144592
Title:
What does `LOGFILE=${1:-/var/log/syslog}` do?
ID:
/2019/05/19/What-does-_LOGFILE___1_-_var_log_syslog__-do_
Created:
May 19, 2019
Edited: February 12, 2022
Upload:
April 8, 2024
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The command: LOGFILE=${1:-/var/log/syslog} is shorthand for:
if [[ "$1" == "" ]] # if parameter 1 is blank
then
LOGFILE="/var/log/syslog" # LOGFILE set to /var/log/syslog
else
LOGFILE="$1" # LOGFILE set to parameter 1
fi
If parameter 1 is not passed you see:
If you pass paraemeter 1:
journalctl -b > /tmp/messages
yad-logfile /tmp/messages
you see:
The original code in question link was modified:
#!/bin/bash
# NAME: yad-logfile
# DATE: May 19, 2019.
# From: https://sourceforge.net/p/yad-dialog/wiki/LogViewer/
# This script demonstrates new features of list dialog. Script displays content
# of specified log file and mark some special strings: with word "kernel" by
# setting italic font, with word "error" by light yellow background and with
# word "warn" by pink background
LOGFILE=${1:-/var/log/syslog}
PARSER='{font=""; color="#FFFFFF"}; \
/CRON/ {font="italic"}; \
/smartd/ {color="#FFF4B8"}; \
/upower/ {color="#FFD0D8"}; \
OFS="\n" {print $1 " " $2, $3, $4, substr($5,0,index($5,":")-1), \
substr($0,index($0,$6)), font, color; fflush()}'
cat $LOGFILE | awk "$PARSER" | \
yad --title="Log viewer" --window-icon=logviewer \
--button=gtk-close --geometry 600x350 \
--list --text="Content of $LOGFILE" \
--column Date --column Time --column Host \
--column Tag --column Message:TIP \
--column @font@ --column @back@
exit $?