Comparison of Shell variables

Two comparison of parameters


[Email protected] shell]# VI test.sh
[email protected] shell]# cat test.sh
#!/bin/bash
if [$1-ge];
Then ECHO-E "\033[41;37m < parameter is not correct, the first number is smaller than the second one, quit this operation! > \033[0m "
Else
echo "Start and End time is: ' Date-d" $ days ago "+%y%m%d"--' date-d ' day Ago "+%y%m%d";
Fi
[Email protected] shell]#./test.sh 1 2
Starting and ending times are: 20141116--20141117
[Email protected] shell]#./test.sh 2 1
< parameter is not correct, the first number is smaller than the second one, quit this operation! >
[Email protected] shell]#./test.sh 2 8
Starting and ending times are: 20141110--20141116
[Email protected] shell]#./test.sh 1 90
Starting and ending times are: 20140820--20141117
[Email protected] shell]#./test.sh 1 100
Starting and ending times are: 20140810--20141117
[Email protected] shell]#./test.sh 1 1
< parameter is not correct, the first number is smaller than the second one, quit this operation! >
[Email protected] shell]#

cleanup.sh
#!/bin/bash
Log_dir=/var/Logroot_uid=0 # Only users with a user ID variable $uid a value of 0 have root privileges.LINES=50 # Default number of rowsE_xcd=66 # exit code values that cannot be entered into the directoryE_notroot=67 # code values that are not exited when the root user is not# must be run as root user, the following is detectedIf [ "$UID" -Ne"$ROOT _uid" ]ThenEcho"Must is root to run this script." Exit$E _notrootFiIf [ -N"$" ]# test whether a command-line argument is provided (that is, the test command-line argument has at least one parameter)ThenLines=$ElseLines=$LINES# Default, if not specified in command line.Fi# Stephane Chazelas suggested that#+ below is a better way to detect command-line arguments,#+ but it's still a bit more advanced for now.## e_wrongargs=65 # is not a numeric parameter (parameter format is not correct) when the exit code## case "$" in# "") lines=50;;# *[!0-9]*) echo "Usage: ' basename $ ' file-to-cleanup"; Exit $E _wrongargs;;# *) lines=$1;# ESAC##* can jump to the "loop" chapter to read the first part to understand the above code meaning.CD $LOG _dirIf [ ' PWD ' != "$LOG _dir" ] # can also be used if ["$PWD"! = "$LOG _dir"] # What if the working directory is not in/var/log?ThenEcho"Can ' t change to $LOG _dir." Exit$E _xcdFi #在操作清空日志文件之前再次检查是否在正确的目录里# you can determine again in the correct directory as follows:## Cd/var/log | | {# echo "Cannot change to necessary directory." >&2# exit $E _xcd;# }Tail-$lines messages> mesg.  Temp # Saves the message log file with the last few lines of log information to the temporary file.  MV MESG.  Temp Messages # then overwrites the messages log file with temporary files # cat/dev/null > Messages#* The above sentence empties the messages log file, This keeps the last few lines as above. Security cat /dev/null > wtmp # ': > Wtmp ' and ' > wtmp ' have The same effect. echo "Logs cleaned up." exit 0                 

Comparison of Shell variables