I have a file that contains directory names:
my_list.txt :
/tmp /var/tmp I'd like to check in Bash before I'll add a directory name if that name already exists in the file.
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问题:
回答1:
grep -Fxq "$FILENAME" my_list.txt The exit status is 0 (true) if the name was found, 1 (false) if not, so:
if grep -Fxq "$FILENAME" my_list.txt then # code if found else # code if not found fi Here are the relevant sections of the man page for grep:
grep [options] PATTERN [FILE...] -F, --fixed-strings Interpret PATTERN as a list of fixed strings, separated by new- lines, any of which is to be matched. -x, --line-regexp Select only those matches that exactly match the whole line. -q, --quiet, --silent Quiet; do not write anything to standard output. Exit immedi- ately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option. 回答2:
Regarding the following solution:
grep -Fxq "$FILENAME" my_list.txt In case you are wondering (as I did) what -Fxq means in plain English F affects how PATTERN is interpreted (fixed string instead of a regex), x match whole line, q shhhhh... minimal printing
From the man file:
-F, --fixed-strings Interpret PATTERN as a list of fixed strings, separated by newlines, any of which is to be matched. (-F is specified by POSIX.) -x, --line-regexp Select only those matches that exactly match the whole line. (-x is specified by POSIX.) -q, --quiet, --silent Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option. (-q is specified by POSIX.) 回答3:
Three methods in my mind:
1) Short test for a name in a path (I'm not sure this might be your case)
ls -a "path" | grep "name"
2) Short test for a string in a file
grep -R "string" "filepath"
3) Longer bash script using regex:
#!/bin/bash declare file="content.txt" declare regex="\s+string\s+" declare file_content=$( cat "${file}" ) if [[ " $file_content " =~ $regex ]] # please note the space before and after the file content then echo "found" else echo "not found" fi exit This should be quicker if you have to test multiple string on a file content using a loop for example changing the regex at any cicle.
回答4:
Simpler way:
if grep "$filename" my_list.txt > /dev/null then ... found else ... not found fi Tip: send to /dev/null if you want command's exit status, but not outputs.
回答5:
If I understood your question correctly, this should do what you need.
- you can specifiy the directory you would like to add through $check variable
- if the directory is already in the list, the output is "dir already listed"
- if the directory is not yet in the list, it is appended to my_list.txt
In one line: check="/tmp/newdirectory"; [[ -n $(grep "^$check\$" my_list.txt) ]] && echo "dir already listed" || echo "$check" >> my_list.txt
回答6:
If you just want to check the existence of one line, you do not need to create a file. E.g.,
if grep -xq "LINE_TO_BE_MATCHED" FILE_TO_LOOK_IN ; then # code for if it exists else # code for if it does not exist fi 回答7:
My version using fgrep
FOUND=`fgrep -c "FOUND" $VALIDATION_FILE` if [ $FOUND -eq 0 ]; then echo "Not able to find" else echo "able to find" fi 回答8:
Easiest and simplest way would be:
isInFile=$(cat file.txt | grep -c "string") if [ $isInFile -eq 0 ]; then #string not contained in file else #string is in file at least once fi grep -c will return the count of how many times the string occurs in the file.
回答9:
grep -E "(string)" /path/to/file || echo "no match found" -E option makes grep use regular expressions
回答10:
A grep-less solution, works for me:
MY_LIST=$( cat /path/to/my_list.txt ) if [[ "${MY_LIST}" == *"${NEW_DIRECTORY_NAME}"* ]]; then echo "It's there!" else echo "its not there" fi 回答11:
if grep -q "$Filename$" my_list.txt then echo "exist" else echo "not exist" fi