Print lines matching pattern

Print only lines that match ERROR

sed -n '/ERROR/p' app.log
tool
sed15 commands
tags
sedlinuxdebug

More sed commands

  • Insert line before match
    sed '/^server_name/i # Added by deploy script' nginx.conf

    Insert a comment line before every server_name directive

  • Append line after match
    sed '/^\[defaults\]/a ansible_python_interpreter=/usr/bin/python3' ansible.cfg

    Append a setting line after the [defaults] header

  • Case-insensitive substitution
    sed 's/error/ERROR/gI' file.txt

    GNU sed /I flag for case-insensitive match

  • Multiple expressions
    sed -e 's/foo/bar/g' -e 's/baz/qux/g' file.txt

    Apply multiple substitutions in one command

  • Strip leading/trailing whitespace
    sed 's/^[[:space:]]*//;s/[[:space:]]*$//' file.txt

    Trim leading and trailing whitespace from each line

all 15 sed commands