I have a script called "upcall" which calls 4 different scripts. In upcall I call them in the way show. The first part of the script works when I run the script directly (bash upload_cloud1), but does not when its called from the script below. Im sure there is a way to fix this, but just not sure what it is. I have it currently setup in crontab to run every 15 mins to check for used space.
#!/bin/bash
if [[ "`pidof -x $(basename $0) -o %PPID`" ]]; then
echo "This script is already running with PID `pidof -x $(basename $0) -o %PPID`"
exit; fi
count=$(</opt/rclone/scripts/upcount)
size=$(df -k /dev/sda2 | tail -1 | awk '{print $3}')
if [ "$size" -gt "234003200" ]; then
bash /opt/rclone/scripts/upload_cloud${count}
else
echo "Not full yet"
fi
In a shell script, how do I echo all shell commands called and expand any variable names?
For example, given the following line:
ls $DIRNAME
I would like the script to run the command and display the following
ls /full/path/to/some/dir
The purpose is to save a log of all shell commands called and their arguments. Is there perhaps a better way of generating such a log?
set -x or set -o xtrace expands variables and prints a little + sign before the line.
set -v or set -o verbose does not expand the variables before printing.
Use set +x and set +v to turn off the above settings.
On the first line of the script, one can put #!/bin/sh -x (or -v) to have the same effect as set -x (or -v) later in the script.
The above also works with /bin/sh.
See the bash-hackers' wiki on set attributes, and on debugging.
$ cat shl
#!/bin/bash
DIR=/tmp/so
ls $DIR
$ bash -x shl
+ DIR=/tmp/so
+ ls /tmp/so
$
set -x will give you what you want.
Here is an example shell script to demonstrate:
#!/bin/bash
set -x #echo on
ls $PWD
This expands all variables and prints the full commands before output of the command.
Output:
+ ls /home/user/
file1.txt file2.txt
I use a function to echo and run the command:
#!/bin/bash
# Function to display commands
exe() { echo "\$ $#" ; "$#" ; }
exe echo hello world
Which outputs
$ echo hello world
hello world
For more complicated commands pipes, etc., you can use eval:
#!/bin/bash
# Function to display commands
exe() { echo "\$ ${#/eval/}" ; "$#" ; }
exe eval "echo 'Hello, World!' | cut -d ' ' -f1"
Which outputs
$ echo 'Hello, World!' | cut -d ' ' -f1
Hello
You can also toggle this for select lines in your script by wrapping them in set -x and set +x, for example,
#!/bin/bash
...
if [[ ! -e $OUT_FILE ]];
then
echo "grabbing $URL"
set -x
curl --fail --noproxy $SERV -s -S $URL -o $OUT_FILE
set +x
fi
shuckc's answer for echoing select lines has a few downsides: you end up with the following set +x command being echoed as well, and you lose the ability to test the exit code with $? since it gets overwritten by the set +x.
Another option is to run the command in a subshell:
echo "getting URL..."
( set -x ; curl -s --fail $URL -o $OUTFILE )
if [ $? -eq 0 ] ; then
echo "curl failed"
exit 1
fi
which will give you output like:
getting URL...
+ curl -s --fail http://example.com/missing -o /tmp/example
curl failed
This does incur the overhead of creating a new subshell for the command, though.
According to TLDP's Bash Guide for Beginners: Chapter 2. Writing and debugging scripts:
2.3.1. Debugging on the entire script
$ bash -x script1.sh
...
There is now a full-fledged debugger for Bash, available at SourceForge. These debugging features are available in most modern versions of Bash, starting from 3.x.
2.3.2. Debugging on part(s) of the script
set -x # Activate debugging from here
w
set +x # Stop debugging from here
...
Table 2-1. Overview of set debugging options
Short | Long notation | Result
-------+---------------+--------------------------------------------------------------
set -f | set -o noglob | Disable file name generation using metacharacters (globbing).
set -v | set -o verbose| Prints shell input lines as they are read.
set -x | set -o xtrace | Print command traces before executing command.
...
Alternatively, these modes can be specified in the script itself, by
adding the desired options to the first line shell declaration.
Options can be combined, as is usually the case with UNIX commands:
#!/bin/bash -xv
Another option is to put "-x" at the top of your script instead of on the command line:
$ cat ./server
#!/bin/bash -x
ssh user#server
$ ./server
+ ssh user#server
user#server's password: ^C
$
You can execute a Bash script in debug mode with the -x option.
This will echo all the commands.
bash -x example_script.sh
# Console output
+ cd /home/user
+ mv text.txt mytext.txt
You can also save the -x option in the script. Just specify the -x option in the shebang.
######## example_script.sh ###################
#!/bin/bash -x
cd /home/user
mv text.txt mytext.txt
##############################################
./example_script.sh
# Console output
+ cd /home/user
+ mv text.txt mytext.txt
Type "bash -x" on the command line before the name of the Bash script. For instance, to execute foo.sh, type:
bash -x foo.sh
Combining all the answers I found this to be the best, simplest
#!/bin/bash
# https://stackoverflow.com/a/64644990/8608146
exe(){
set -x
"$#"
{ set +x; } 2>/dev/null
}
# example
exe go generate ./...
{ set +x; } 2>/dev/null from https://stackoverflow.com/a/19226038/8608146
If the exit status of the command is needed, as mentioned here
Use
{ STATUS=$?; set +x; } 2>/dev/null
And use the $STATUS later like exit $STATUS at the end
A slightly more useful one
#!/bin/bash
# https://stackoverflow.com/a/64644990/8608146
_exe(){
[ $1 == on ] && { set -x; return; } 2>/dev/null
[ $1 == off ] && { set +x; return; } 2>/dev/null
echo + "$#"
"$#"
}
exe(){
{ _exe "$#"; } 2>/dev/null
}
# examples
exe on # turn on same as set -x
echo This command prints with +
echo This too prints with +
exe off # same as set +x
echo This does not
# can also be used for individual commands
exe echo what up!
For zsh, echo
setopt VERBOSE
And for debugging,
setopt XTRACE
To allow for compound commands to be echoed, I use eval plus Soth's exe function to echo and run the command. This is useful for piped commands that would otherwise only show none or just the initial part of the piped command.
Without eval:
exe() { echo "\$ $#" ; "$#" ; }
exe ls -F | grep *.txt
Outputs:
$
file.txt
With eval:
exe() { echo "\$ $#" ; "$#" ; }
exe eval 'ls -F | grep *.txt'
Which outputs
$ exe eval 'ls -F | grep *.txt'
file.txt
For csh and tcsh, you can set verbose or set echo (or you can even set both, but it may result in some duplication most of the time).
The verbose option prints pretty much the exact shell expression that you type.
The echo option is more indicative of what will be executed through spawning.
http://www.tcsh.org/tcsh.html/Special_shell_variables.html#verbose
http://www.tcsh.org/tcsh.html/Special_shell_variables.html#echo
Special shell variables
verbose
If set, causes the words of each command to be printed, after history substitution (if any). Set by the -v command line option.
echo
If set, each command with its arguments is echoed just before it is executed. For non-builtin commands all expansions occur before echoing. Builtin commands are echoed before command and filename substitution, because these substitutions are then done selectively. Set by the -x command line option.
$ cat exampleScript.sh
#!/bin/bash
name="karthik";
echo $name;
bash -x exampleScript.sh
Output is as follows:
I have a bash script that I want to expand to support piping json into.
Example:
echo '{}' | myscript store
So, I tried the following:
local value="$1"
if [[ -z "$value" ]]; then
while read -r piped; do
value=$piped
done;
fi
Which works in a simple case above, but doing:
cat input.json | myscript store
Only get's the last line of the file input.json, it does not handle every line.
How can I support all cases of piping?
The following works:
if [[ -z "$value" && ! -t 0 ]]; then
while read -r piped; do
value+=$piped
done;
fi
The trick was using += and also checking ! -t 0 which checks if we are piping.
If you want to behave like cat, why not use it?
#! /bin/bash
value="$( cat "$#" )"
I wrote a program in c++ and now I have a binary. I have also generated a bunch of tests for testing. Now I want to automate the process of testing with bash. I want to save three things in one execution of my binary:
execution time
exit code
output of the program
Right now I am stack up with a script that only tests that binary does its job and returns 0 and doesn't save any information that I mentioned above. My script looks like this
#!/bin/bash
if [ "$#" -ne 2 ]; then
echo "Usage: testScript <binary> <dir_with_tests>"
exit 1
fi
binary="$1"
testsDir="$2"
for test in $(find $testsDir -name '*.txt'); do
testname=$(basename $test)
encodedTmp=$(mktemp /tmp/encoded_$testname)
decodedTmp=$(mktemp /tmp/decoded_$testname)
printf 'testing on %s...\n' "$testname"
if ! "$binary" -c -f $test -o $encodedTmp > /dev/null; then
echo 'encoder failed'
rm "$encodedTmp"
rm "$decodedTmp"
continue
fi
if ! "$binary" -u -f $encodedTmp -o $decodedTmp > /dev/null; then
echo 'decoder failed'
rm "$encodedTmp"
rm "$decodedTmp"
continue
fi
if ! diff "$test" "$decodedTmp" > /dev/null ; then
echo "result differs with input"
else
echo "$testname passed"
fi
rm "$encodedTmp"
rm "$decodedTmp"
done
I want save output of $binary in a variable and not send it into /dev/null. I also want to save time using time bash function
As you asked for the output to be saved in a shell variable, I tried answering this without using output redirection – which saves output in (temporary) text files (which then have to be cleaned).
Saving the command output
You can replace this line
if ! "$binary" -c -f $test -o $encodedTmp > /dev/null; then
with
if ! output=$("$binary" -c -f $test -o $encodedTmp); then
Using command substitution saves the program output of $binary in the shell variable. Command substitution (combined with shell variable assignment) also allows exit codes of programs to be passed up to the calling shell so the conditional if statement will continue to check if $binary executed without error.
You can view the program output by running echo "$output".
Saving the time
Without a more sophisticated form of Inter-Process Communication, there’s no way for a shell that’s a sub-process of another shell to change the variables or the environment of its parent process so the only way that I could save both the time and the program output was to combine them in the one variable:
if ! time-output=$(time "$binary" -c -f $test -o $encodedTmp) 2>&1); then
Since time prints its profiling information to stderr, I use the parentheses operator to run the command in subshell whose stderr can be redirected to stdout. The programming output and the output of time can be viewed by running echo "$time-output" which should return something similar to:
<program output>
<blank line>
real 0m0.041s
user 0m0.000s
sys 0m0.046s
You can get the process status in bash by using $? and print it out by echo $?.
And to catch the output of time, you could use sth like that
{ time sleep 1 ; } 2> time.txt
Or you can save the output of the program and execution time at once
(time ls) > out.file 2>&1
You can save output to a file using output redirection. Just change first /dev/null line:
if ! "$binary" -c -f $test -o $encodedTmp > /dev/null; then
to
if ! "$binary" -c -f $test -o $encodedTmp > prog_output; then
then change second and third /dev/null lines respectively:
if ! "$binary" -u -f $encodedTmp -o $decodedTmp >> prog_output; then
if ! diff "$test" "$decodedTmp" >> prog_output; then
To measure program execution put
start=$(date +%s)
on the first line
then
end=$(date +%s)
echo "Execution time in seconds: " $((end-start)) >> prog_output
on the end.
How do I pass a command as an argument to a bash script?
In the following script, I attempted to do that, but it's not working!
#! /bin/sh
if [ $# -ne 2 ]
then
echo "Usage: $0 <dir> <command to execute>"
exit 1;
fi;
while read line
do
$($2) $line
done < $(ls $1);
echo "All Done"
A sample usage of this script would be
./myscript thisDir echo
Executing the call above ought to echo the name of all files in the thisDir directory.
First big problem: $($2) $line executes $2 by itself as a command, then tries to run its output (if any) as another command with $line as an argument to it. You just want $2 $line.
Second big problem: while read ... done < $(ls $1) doesn't read from the list of filenames, it tries to the contents of a file specified by the output of ls -- this will fail in any number of ways depending on the exact circumstances. Process substitution (while read ... done < <(ls $1)) would do more-or-less what you want, but it's a bash-only feature (i.e. you must start the script with #!/bin/bash, not #!/bin/sh). And anyway it's a bad idea to parse ls, you should almost always just use a shell glob (*) instead.
The script also has some other potential issues with spaces in filenames (using $line without double-quotes around it, etc), and weird stylistic oddities (you don't need ; at the end of a line in shell). Here's my stab at a rewrite:
#! /bin/sh
if [ $# -ne 2 ]; then
echo "Usage: $0 <dir> <command to execute>"
exit 1
fi
for file in "$1"/*; do
$2 "$file"
done
echo "All done"
Note that I didn't put double-quotes around $2. This allows you to specify multiword commands (e.g. ./myscript thisDir "cat -v" would be interpreted as running the cat command with the -v option, rather than trying to run a command named "cat -v"). It would actually be a bit more flexible to take all arguments after the first one as the command and its argument, allowing you to do e.g. ./myscript thisDir cat -v, ./myscript thisDir grep -m1 "pattern with spaces", etc:
#! /bin/sh
if [ $# -lt 2 ]; then
echo "Usage: $0 <dir> <command to execute> [command options]"
exit 1
fi
dir="$1"
shift
for file in "$dir"/*; do
"$#" "$file"
done
echo "All done"
your command "echo" command is "hidden" inside a sub-shell from its argments in $line.
I think I understand what your attempting in with $($2), but its probably overkill, unless this isn't the whole story, so
while read line ; do
$2 $line
done < $(ls $1)
should work for your example with thisDir echo. If you really need the cmd-substitution and the subshell, then put you arguments so they can see each other:
$($2 $line)
And as D.S. mentions, you might need eval before either of these.
IHTH
you could try: (in your codes)
echo "$2 $line"|sh
or the eval:
eval "$2 $line"