So I'm beginning making bash scripts. I can do basic stuff, but that's it.
I want to make something so when I type in:
./myprogram -t
It will do "echo true"
And if I type in:
./myprogram -f
It will do "echo false"
Thanks in advance
The positional parameters are available through the variables $1 $2 etc.
There are many ways to implement the contition. You could use an if statement:
#!/bin/bash
if [ "$1" = -t ]
then
echo true
elif [ "$1" = -f ]
then
echo false
fi
A case statement:
#!/bin/bash
case "$1" in
-t) echo true ;;
-f) echo false ;;
esac
Or a short-circuit:
#!/bin/bash
[ "$1" = -t ] && echo true
[ "$1" = -f ] && echo false
For more complex cases consider using the getopt or the getopts libraries.
The word for what you are calling an "option" is typically referred to as an argument in programming. You should read more about how to handle arguments in bash by reading everything at http://tldp.org/LDP/abs/html/othertypesv.html . To answer your direct question the script might look like this:
#!/bin/bash
if [[ $# -eq 0 ]]; then
echo 'No Arguments'
exit 0
fi
if [ $1 = "-f" ]; then
echo false
elif [ $1 = "-t" ]; then
echo true
fi
Related
have some problem with shell script.
In our office we set up only few commands, that available for devs when they are trying ssh to server. It is configured with help of .ssh/authorized_keys file and available command for user there is bash script:
#!/bin/sh
if [[ $1 == "--help" ]]; then
cat <<"EOF"
This script has the purpose to let people remote execute certain commands without logging into the system.
For this they NEED to have a homedir on this system and uploaded their RSA public key to .ssh/authorized_keys (via ssh-copy-id)
Then you can alter that file and add some commands in front of their key eg :
command="/usr/bin/dev.sh",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty
The user will do the following : ssh testuser#server tail testserver.example.com/2017/01/01/user.log
EOF
exit 0;
fi
# set global variable
set $SSH_ORIGINAL_COMMAND
# set the syslog path where the files can be found
PATH="/opt/syslog/logs"
# strip ; or any other unwanted signs out of the command, this prevents them from breaking out of the setup command
if [[ $1 != "" ]]; then
COMMAND=$1
COMMAND=${COMMAND//[;\`]/}
fi
if [[ $2 != "" ]]; then
ARGU1=$2
ARGU1=${ARGU1//[;\`]/}
fi
if [[ $3 != "" ]]; then
ARGU2=$3
ARGU2=${ARGU2//[;\`]/}
fi
if [[ $4 != "" ]]; then
ARGU3=$4
ARGU3=${ARGU3//[;\`]/}
fi
# checking for the commands
case "$COMMAND" in
less)
ARGU2=${ARGU1//\.\./}
FILE=$PATH/$ARGU1
if [ ! -f $FILE ]; then
echo "File doesn't exist"
exit 1;
fi
#echo " --------------------------------- LESS $FILE"
/usr/bin/less $FILE
;;
grep)
if [[ $ARGU2 == "" ]]; then
echo "Pls give a filename"
exit 1
fi
if [[ $ARGU1 == "" ]]; then
echo "Pls give a string to search for"
exit 1
fi
ARGU2=${ARGU2//\.\./}
FILE=$PATH/$ARGU2
/usr/bin/logger -t restricted-command -- "------- $USER Executing grep $ARGU1 \"$ARGU2\" $FILE"
if [ ! -f $FILE ]; then
echo "File doesn't exist"
/usr/bin/logger -t restricted-command -- "$USER Executing $#"
exit 1;
fi
/bin/grep $ARGU1 $FILE
;;
tail)
if [[ $ARGU1 == "" ]]; then
echo "Pls give a filename"
exit 1
fi
ARGU1=${ARGU1//\.\./}
FILE=$PATH/$ARGU1
if [ ! -f $FILE ]; then
echo "File doesn't exist"
/usr/bin/logger -t restricted-command -- "$USER Executing $# ($FILE)"
exit 1;
fi
/usr/bin/tail -f $FILE
;;
cat)
ARGU2=${ARGU1//\.\./}
FILE=$PATH/$ARGU1
if [ ! -f $FILE ]; then
echo "File doesn't exist"
exit 1;
fi
/bin/cat $FILE
;;
help)
/bin/cat <<"EOF"
# less LOGNAME (eg less testserver.example.com/YYYY/MM/DD/logfile.log)
# grep [ARGUMENT] LOGNAME
# tail LOGNAME (eg tail testserver.example.com/YYYY/MM/DD/logfile.log)
# cat LOGNAME (eg cat testserver.example.com/YYYY/MM/DD/logfile.log)
In total the command looks like this : ssh user#testserver.example.com COMMAND [ARGUMENT] LOGFILE
EOF
/usr/bin/logger -t restricted-command -- "$USER HELP requested $#"
exit 1
;;
*)
/usr/bin/logger -s -t restricted-command -- "$USER Invalid command $#"
exit 1
;;
esac
/usr/bin/logger -t restricted-command -- "$USER Executing $#"
The problem is next:
when i try to exec some command, it takes only first argument, if i do recursion in files by using {n,n1,n2} - it doesn't work:
[testuser#local ~]$ ssh testuser#syslog.server less srv1838.example.com/2017/02/10/local1.log |grep 'srv2010' | wc -l
0
[testuser#local ~]$ ssh testuser#syslog.server less srv2010.example.com/2017/02/10/local1.log |grep 'srv2010' | wc -l
11591
[testuser#local ~]$ ssh testuser#syslog.server less srv{1838,2010}.example.com/2017/02/10/local1.log |grep 'srv2010' | wc -l
0
[testuser#local ~]$ ssh testuser#syslog.server less srv{2010,1838}.example.com/2017/02/21/local1.log |grep 'srv2010' | wc -l
11591
Could someone help me, how can i parse\count command arguments to make it work?
Thank you and have a nice day!
The number of arguments for a bash script would be $#. As a quick example:
#!/bin/bash
narg=$#
typeset -i i
i=1
while [ $i -le $narg ] ; do
echo " $# $i: $1"
shift
i=$i+1
done
gives, for bash tst.sh a b {c,d}
4 1: a
3 2: b
2 3: c
1 4: d
In your script, the command to execute (cat, less, ...) gets explicitly only the second argument to the script. If you want to read all arguments, you should do something like this (note: only a hint, removed all sorts of checks etc..)
command="$1"
shift
case $command in
(grep) pattern="$1"
shift
while [ $# -gt 0 ] ; do
grep "$pattern" "$1"
shift
done
;;
esac
note: added some quotes as comment suggested, but, being only a hint, you should carefully look at quoting and your checks in your own script.
Less command working now:
case "$COMMAND" in
less)
if [[ $ARGU1 == "" ]]; then
echo "Pls give a filename"
exit 1
fi
FILES_LIST=${#:2}
FILE=(${FILES_LIST//\.\./})
for v in "${FILE[#]}";do
v=${v//[;\']/}
if [ ! -f $v ]; then
echo "File doesn't exist"
fi
/usr/bin/less $PATH/$v
done;;
tail command works too with 2 and more files, but i can't execute tail -f command on two files unfortunately.
I would need my bash scrip to work either with:
No arguments
./script.sh
Path argument (classic argument, will saved as var to var=$1)
./script.sh /root/home/dir/
With switch -a (with it's own argument)
./script.sh -a picture.jpeg
Or both combined
./script.sh -a picture.jpeg /root/home/dir/
I have something like this:
while getopts ":a:" opt; do
case $opt in
a)
I_ARGUMENT=$OPTARG
echo "A ARGUMENT IS: $OPTARG"
;;
:)
echo "-a requires argument"
;;
esac
done
And then something like this for the path argument:
if [ -z "$1" ]
then
:
else
PATH="$1"
fi
Which obviously doesn't work well (at all) together. Could you help me to combine this two things? Thank you.
How about something like this
pathToHomeSlashDir=~/dir/ #default value will be home/dir/
if [ $# -gt 0 ]
then
while [ $# -gt 0 ]
do
case "$1" in
-a)
if [ $# -gt 1 ]
then
image="$2"
shift
else
echo "Please insert -a argument"
exit
fi
;;
*)
pathToHomeSlashDir="$1"
;;
esac
shift
done
fi
You'd just need to handle the variables then
A recent test I took had a question on the output of the following bash command:
var=; [ -n $var ]; echo $?; [ -z $var ]; echo $?
The results are 0 and 0, indicating the return codes for both unary operators had no errors. This means $var resolves to both null (empty) and 'non-null' (not empty), correct?
How is this possible?
No, it means that [ is unfixably broken. In both cases $var evaluates to nothing, and the commands simply execute [ -n ] and [ -z ] respectively, both of which result in true. If you want to test the value in the variable itself then you must quote it to have it handled properly.
$ var=; [ -n "$var" ]; echo $?; [ -z "$var" ]; echo $?
1
0
You will need to surround $var:
$ [ -n "$var" ]; echo $?
1
Remember that the closing square bracket is just syntactic sugar: you don't need it. That means your line:
$ [ -n $var ]; echo $?
will expand to (since $var is empty):
$ [ -n ]; echo $?
The above asks: "is the string ']' non-empty?" And the answer is yes.
It's surprising indeed. If you were to try the same with the bashism [[ syntax, you'd get 1 and 0 as results. I reckon this is a bug.
var=; [[ -n $var ]]; echo $?; [[ -z $var ]]; echo $?
or, as Ignacio points out and as in fact I have always been doing intuitively, with defensive coding and quoting:
var=; [[ -n "$var" ]]; echo $?; [[ -z "$var" ]]; echo $?
It's surprising to me that [ behaves this way, because it's a builtin:
$ type [
[ is a shell builtin
Just did a little test and the system command [ behaves in the same broken way as the builtin. So probably it's buggy for compatibility:
var=; /usr/bin/\[ -n $var ]; echo $?; /usr/bin/\[ -z $var ]; echo $?
I'm trying to fit a script for linux onto my WD world edition drive.
The script is written for Bash (debian) but my WD only runs busybox (with ash). Despite this, I have gotten most functionality in there just from using Google. There is only one operator i have not found a counterpart to, the =~ operator
How can i port the functionality of the =~ operator from the old script to ash?
Script:
#! /bin/bash
# posttorrent.sh by Killemov
{
# Log file, file where we tell what events have been processed.
LOG_FILE=/var/log/posttorrent.log
# Username for transmission remote.
TR_USERNAME="username"
# Password for transmission remote.
TR_PASSWORD="password"
# Get current time.
NOW=$(date +%Y-%m-%d\ %H:%M:%S)
# Source directory, should not be changed.
SRC_DIR="${TR_TORRENT_DIR}/${TR_TORRENT_NAME}"
# Directory to store the un-compressed files in..
DEST_DIR="${TR_TORRENT_DIR}/${TR_TORRENT_NAME}/"
# This parameter string could be passed from Transmission in the future.
TR_TORRENT_PARAMETER="EXTRACT SLEEP1h"
echo "text"
if [ -e "$SRC_DIR/keep" ]; then
TR_TORRENT_PARAMETER="$TR_TORRENT_PARAMETER KEEP"
fi
if [ -e "$SRC_DIR/exit" ]; then
TR_TORRENT_PARAMETER="EXIT"
fi
# Actual processing starts here.
if [[ "$TR_TORRENT_PARAMETER" =~ "EXIT" ]]; then
echo $NOW "Exiting $TR_TORRENT_NAME" >> $LOG_FILE
exit 0
fi
echo "text2"
if [[ "$TR_TORRENT_PARAMETER" =~ "EXTRACT" ]]; then
cd $TR_TORRENT_DIR
if [ -d "$SRC_DIR" ]; then
IFS=$'\n'
unset RAR_FILES i
for RAR_FILE in $( find "$SRC_DIR" -iname "*.rar" ); do
if [[ $RAR_FILE =~ .*part.*.rar ]]; then
if [[ $RAR_FILE =~ .*part0*1.rar ]]; then
RAR_FILES[i++]=$RAR_FILE
fi
else
RAR_FILES[i++]=$RAR_FILE
fi
done
unset IFS
if [ ${#RAR_FILES} -gt 0 ]; then
for RAR_FILE in "$(eval \$$RAR_FILES[#])"; do
unrar x -inul "$RAR_FILE" "$DEST_DIR"
if [ $? -gt 0 ]; then
echo $NOW "Error unrarring $TR_TORRENT_NAME" >> $LOG_FILE
transmission-remote -n $TR_USERNAME:$TR_PASSWORD -t$TR_TORRENT_ID --verify --start
exit 0
fi
done
if [[ ! "$TR_TORRENT_PARAMETER" =~ "KEEP" ]]; then
SLEEP=$(expr match "$TR_TORRENT_PARAMETER" '.*SLEEP\([0-9a-zA-Z]*\)')
if [ ${#SLEEP} -gt 0 ]; then
sleep $SLEEP
fi
transmission-remote -n $TR_USERNAME:$TR_PASSWORD -t$TR_TORRENT_ID --remove-and-delete
fi
echo $NOW "Unrarred $TR_TORRENT_NAME" >> $LOG_FILE
fi
fi
fi
} &
(i had some trouble with indirect references, i hoped i fixed that correctly)
Well for the $VARIABLE =~ PATERN you should be able to use the:
echo "$VARIABLE" | grep -E PATTERN
But I think you will have a little bit of trouble with the arithmetical expressions i++ as well - if it's implemented, then you still need to use the i=$(($i + 1)) syntax, if it's not implemented, then the i=$(expr $i + 1) syntax.
I presume you're reason for the IFS=$'\n' is to split the find on newlines, but you're probably better off with issuing the find into a temporary file, and then doing a while read line; do ... done <$tmpfile,
Additionally, I'm not certain if all versions of busybox ash support arrays, so you may have a problem there as well.
DISPLAY_HEADER=1
if [ "$1" != "test" -o "$1" != "test2" ]
then
if [ $DISPLAY_HEADER == 1 ]; then
DISPLAY_HEADER=0
echo "sdasa "
echo $1
fi
fi
its display sdasa and -o is not working ?
what is wrong ?
you can use case/esac
case "$1" in
test|test2)
# do something
*)
# set display data
;;
esac