I have a "pseudo term" wrapper written in bash. it takes input and sends it to a device with the "nc" command. I want it to handle pipes and redirects. This is what I have.
while read -ep "${1}> " CMD
do
[[ ${CMD} =~ '|' ]] && SEP=1
[[ ${CMD} =~ '>' ]] && SEP=2
[[ -z ${SEP} ]] && echo "${CMD}"|nc -4u -w1 ${1} 65432 && continue
CMD1=$(echo ${CMD}|awk -F '[|>]' '{print $1}')
CMD2=$(echo ${CMD}|awk -F '[|>]' '{print $2}')
[[ ${SEP} -eq 1 ]] && echo "${CMD1}"|nc -4u -w1 ${1} 65432 | ${CMD2}
[[ ${SEP} -eq 2 ]] && echo "${CMD1}"|nc -4u -w1 ${1} 65432 > ${CMD2}
done
If checks the command variable to see if it contains a pipe or redirect.
If it does not, then send the command, as-is, to nc.
If there is a pipe or redirect, then break the command into two: the part before, and the part after the pipe or redirect.
Send the first part to "nc", and the output to the second part.
It works. But, it can handle only 1 pipe or redirect. I would like it to be able to handle an indeterminate number of pipes and redirects.
Thanks.
Related
I'm trying to automate a build process by replacing .js chunks for particular lines in my main.config.php file. When I run the following code:
declare -a js_strings=("footer." "footerJQuery." "headerCSS." "headerJQuery.")
build_path="./build/build"
config_path="./system/Config/main.config.php"
while read -r line;
do
for js_string in ${js_strings[#]}
do
if [[ $line == *$js_string* ]]
then
for js_file in "$build_path"/*
do
result="${js_file//[^.]}"
if [[ $js_file == *$js_string* ]] && [[ ${#result} -eq 3 ]]
then
sed -i "s/$line/$line$(basename $js_file)\";/g" $config_path
fi
done
fi
done
done < "$config_path"
I get this message back, and file has not been updated/edited:
sed: 1: "./system/Config/main.co ...": invalid command code .
I haven't been able to find anything in my searches that pertain to this specific message. Does anyone know what I need to change/try to get the specific lines replaced in my .php file?
Updated script with same message:
declare -a js_strings=("footer." "footerJQuery." "headerCSS." "headerJQuery.")
build_path="./build/build"
config_path="./system/Config/main.config.php"
while read -r line;
do
for js_string in ${js_strings[#]}
do
if [[ $line == *$js_string* ]]
then
for js_file in "$build_path"/*
do
result="${js_file//[^.]}"
if [[ $js_file == *$js_string* ]] && [[ ${#result} -eq 3 ]]
then
filename=$(basename $js_file)
newline="${line//$js_string*/$filename\";}"
echo $line
echo $newline
sed -i "s\\$line\\$newline\\g" $config_path
echo ""
fi
done
fi
done
done < "$config_path"
Example $line:
$config['public_build_header_css_url'] = "http://localhost:8080/build/headerCSS.js";
Example $newline:
$config['public_build_header_css_url'] = "http://localhost:8080/build/headerCSS.7529a73071877d127676.js";
Updated script with changes suggested by #Vercingatorix:
declare -a js_strings=("footer." "footerJQuery." "headerCSS." "headerJQuery.")
build_path="./build/build"
config_path="./system/Config/main.config.php"
while read -r line;
do
for js_string in ${js_strings[#]}
do
if [[ $line == *$js_string* ]]
then
for js_file in "$build_path"/*
do
result="${js_file//[^.]}"
if [[ $js_file == *$js_string* ]] && [[ ${#result} -eq 3 ]]
then
filename=$(basename $js_file)
newline="${line//$js_string*/$filename\";}"
echo $line
echo $newline
linenum=$(grep -n "^${line}\$" ${config_path} | cut -d':' -f 1 )
echo $linenum
[[ -n "${linenum}" ]] && sed -i "${linenum}a\\
${newline}
;${linenum}d" ${config_path}
echo ""
fi
done
fi
done
done < "$config_path"
Using sed's s command to replace a line of that complexity is a losing proposition, because whatever delimiter you choose may appear in the line and mess things up. If these are in fact entire lines, it is better to delete them and insert a new one:
linenum=$(fgrep -nx -f "${line}" "${config_path}" | awk -F : "{print \$1}" )
[[ -n "${linenum}" ]] && sed -i "" "${linenum}a\\
${newline}
;${linenum}d" "${config_path}"
What this does is search for the line number of the line that matches $line in its entirety, then extracts the line number portion. fgrep is necessary otherwise the symbols in your file are interpreted as regular expressions. If there was a match, then it runs sed, appending the new line (a) and deleting the old one (d).
I'm trying to echo "It was not found" if the netstat returns no result. But, if it does return a result, then to display the netstat results.
I'm trying to google for what I'm using and can't find much about it.
#!/bin/bash
echo "Which process would you like to run netstat against?"
read psname
echo "Looking for '$psname'"
sleep 2
command=$(netstat -tulpn | grep -e $psname)
[[ ! -z $command ]]
It's to do with the [[ ! -z $command ]]
[[ ! -z $command ]] doesn't 'show' you any output.
Use a if/else setup to show the result;
if [[ ! -z $command ]]; then
echo "$psname was found!"
else
echo "No process named '${psname}' found!"
fi
Or a shorthand variant;
[[ ! -z $command ]] && echo "$psname was found!" || echo "No process named '${psname}' found!"
Note if the user input may contain a space, it's saver to use "" around the grep string;
command=$(netstat -tulpn | grep -e "$psname")
When to wrap quotes around a shell variable?
Do not intercept the output directly. You can instead do something like:
if ! netstat -tulpn | grep -e "$psname"; then
echo "not found" >&2
fi
If grep matches any output, it will print it to stdout. If it mathches nothing, it returns non-zero and the shell will write a message to stderr.
How can I use bash to scan for a specific string of characters in a text file and then use an if then statement to execute a specific command depending on the string?
I am trying to use rsync to back up some raspberry pis from a query string output from an HTML form. I have minimal bash experience and I have been poking and prodding this code for days now and I would love for some advice.
QUERY_STRING will contain something similar to "Backup_To_Comp=tasting-side_backup&subbtn=Submit" with the "Tasting-side_backup" being swapped for other radial button tags as selected.
#!/bin/bash
echo "Content-type: text/html"
echo ""
echo "$QUERY_STRING" > /var/www/cgi-bin/scan.txt
BackupToCompFrom=`echo "$QUERY_STRING" | sed -n 's/^.*Backup_To_Comp=\([^&]*\).*$/\1/p' | sed "s/%20/ /g"`
echo "<html><head><title>What You Said</title></head>"
echo "<body>Here's what you said:"
echo "You entered $BackupToCompFrom in from field."
sleep 1
file="/var/www/cgi-bin/scan.txt"
##echo "$QUERY_STRING"
while IFS='' read -r line || [[ -n "$line" ]];
do
if [[ $line = "tasting-side_backup" ]]; then
echo "GotIt."
rsync pi#192.168.1.1:/home/pi/screenly_assets /home/pi/Downloads
elif [[ $line = "~tasting-main"* ]]; then
print "Tasting Main"
elif [[ $line = "~lodge"* ]]; then
print "Lodge"
elif [[ $line = "~barn"* ]]; then
print "Barn"
else
print "Please select a pi to copy from!"
fi
done
How can I use bash to scan for a specific string of characters in a text file and then use an if then statement to execute a specific command depending on the string?
You can use a command in the if statement. Now the exit code for that command is used to determine true or false. For simple searching of a query to a file, you can use grep.
if grep -q "$QUERY_STRING" file; then
The -q is used to prevent any output from grep ending up in stdin.
#!/bin/bash
ipaddr=${1}
rdlnk=$(readlink /proc/$$/fd/0)
user=""
passwd=""
function get_input() {
if grep -Eq "^pipe:|deleted" <<< "${rdlnk}" || [[ -p "${rdlnk}" ]]; then
while IFS= read -r piped_input || break; do
[[ -z "${ipaddr}" ]] && ipaddr="${piped_input}" && continue
[[ -z "${user}" ]] && user="${piped_input}" && continue
[[ -z "${passwd}" ]] && passwd="${piped_input}" && continue
done
fi
echo "Got that IP address you gave me to work on: ${ipaddr}"
[[ -n "${user}" ]] && echo "[... and that user: ${user}]"
[[ -n "${user}" ]] && echo "[... and that users password: ${passwd}]"
}
get_input
exit 0
Normally it's fine:
$> process_ip.bsh 71.123.123.3
Got that IP address you gave me to work on: 71.123.123.3
But, put the parent into a piped loop and watch out:
$ echo -en "71.123.123.3\nroot\ntoor\n" | while read a; do echo "Parent loop, processing: ${a}"; grep -q '^[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}' <<< "${a}" && ./process_ip.bsh "$a"; done
Parent loop, processing: 71.123.123.3
Got that IP address you gave me to work on: 71.123.123.3
[... and that user: root]
[... and that users password: toor]
Ouch. The parent only wanted to provide the IP Address from its pipe to the child. Presuming that the parent must maintain an open pipe with sensitive data in it at the time of the fork to the child process. How can this be prevented?
process_ip.bsh, like any other process, inherits its standard input from its parent. This line
rdlnk=$(readlink /proc/$$/fd/0)
doesn't do exactly what you think it does. It only contains the name of the file the parent is using for standard input because the script is inheriting its standard input from the parent. ($$ is the process ID of the current shell because .process_ip.bsh is a separate process, not merely a subshell started by the parent.)
If you redirect input to process_ip.bsh, you are in complete control of what it receives.
while read a; do
echo "Parent loop, processing: ${a}"
grep -q '^[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}' <<< "${a}" &&
./process_ip.bsh "$a" < /dev/null
done <<EOF
71.123.123.3
root
toor
EOF
Can anyone see whats wrong here? If I put X|9 in lan.db (or any db in this directory) and run the following code, the IF statement does not work. It's weird! if you echo $LINE, it is indeed pulling X|9 out of lan.db (or any db in this directory) and setting it equal to LINE, but it wont do the comparison.
DBREGEX="^[0-9]|[0-9]$"
shopt -s nullglob
DBARRAY=(databases/*)
i=0
for i in "${!DBARRAY[#]}"; do
cat ${DBARRAY[$i]} | grep -v \# | while read LINE; do
echo "$LINE" (Whats weird is that LINE DOES contain X|9)
if [[ !( $LINE =~ $DBREGEX ) ]]; then echo "FAIL"; fi
done
done
If however I just manually sent LINE="X|9" the same code (minus the while) works fine. ie LINE=X|9 fails, but LINE=9|9 succeeds.
DBREGEX="^[0-9]|[0-9]$"
Comment shopt -s nullglob
Comment DBARRAY=(databases/*)
Comment i=0
Comment for i in "${!DBARRAY[#]}"; do
Comment cat ${DBARRAY[$i]} | grep -v \# | while read LINE; do
LINE="X|9"
if [[ !( $LINE =~ $DBREGEX ) ]]; then echo "FAIL"; fi
Comment done
Comment done
* UPDATE *
UGH I GIVE UP
Now not even this is working...
DBREGEX="^[0-9]|[0-9]$"
LINE="X|9"
if [[ ! $LINE =~ $DBREGEX ]]; then echo "FAIL"; fi
* UPDATE *
Ok, so it looks like I have to escape |
DBREGEX="^[0-9]\|[0-9]$"
LINE="9|9"
echo "$LINE"
if [[ ! $LINE =~ $DBREGEX ]]; then echo "FAIL"; fi
This seems to work ok again
| has a special meaning in a regular expression. ^[0-9]|[0-9]$ means "starts with a digit, or ends with a digit". If you want to match a literal vertical bar, backslash it:
DBREGEX='^[0-9]\|[0-9]$'
for LINE in 'X|9' '9|9' ; do
echo "$LINE"
if [[ ! $LINE =~ $DBREGEX ]] ; then echo "FAIL" ; fi
done
You don't need round brackets in regex evaluation. You script is also creating a sub shell and making a useless use of cat which can be avoided.
Try this script instead:
while read LINE; do
echo "$LINE"
[[ "$LINE" =~ $DBREGEX ]] && echo "PASS" || echo "FAIL"
done < <(grep -v '#' databases/lan.db)